{"id":49909,"date":"2022-12-20T13:25:45","date_gmt":"2022-12-20T13:25:45","guid":{"rendered":"https:\/\/dev.metos.global\/?page_id=49909"},"modified":"2026-05-04T10:42:57","modified_gmt":"2026-05-04T10:42:57","slug":"virtual-sensors","status":"publish","type":"page","link":"https:\/\/metos.global\/en\/virtual-sensors\/","title":{"rendered":"Virtual sensors"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-page\" data-elementor-id=\"49909\" class=\"elementor elementor-49909\" data-elementor-post-type=\"page\">\n\t\t\t\t\t\t<section class=\"elementor-section elementor-top-section elementor-element elementor-element-bfe4d00 elementor-section-boxed elementor-section-height-default elementor-section-height-default\" data-id=\"bfe4d00\" data-element_type=\"section\" data-e-type=\"section\">\n\t\t\t\t\t\t<div class=\"elementor-container elementor-column-gap-no\">\n\t\t\t\t\t<div class=\"elementor-column elementor-col-100 elementor-top-column elementor-element elementor-element-a231ae5\" data-id=\"a231ae5\" data-element_type=\"column\" data-e-type=\"column\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t<div class=\"elementor-element elementor-element-a3c8e77 elementor-widget elementor-widget-heading\" data-id=\"a3c8e77\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">VIRTUAL SENSORS<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t<section class=\"elementor-section elementor-top-section elementor-element elementor-element-9e7d5b7 elementor-section-boxed elementor-section-height-default elementor-section-height-default\" data-id=\"9e7d5b7\" data-element_type=\"section\" data-e-type=\"section\">\n\t\t\t\t\t\t<div class=\"elementor-container elementor-column-gap-default\">\n\t\t\t\t\t<div class=\"elementor-column elementor-col-33 elementor-top-column elementor-element elementor-element-a76537e\" data-id=\"a76537e\" data-element_type=\"column\" data-e-type=\"column\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t<div class=\"elementor-element elementor-element-02b6b47 elementor-widget elementor-widget-heading\" data-id=\"02b6b47\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><a href=\"#vpd\">VAPOUR PRESSURE DEFICIT<\/a><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t<div class=\"elementor-column elementor-col-33 elementor-top-column elementor-element elementor-element-09fa2b5\" data-id=\"09fa2b5\" data-element_type=\"column\" data-e-type=\"column\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t<div class=\"elementor-element elementor-element-af56434 elementor-widget elementor-widget-heading\" data-id=\"af56434\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><a href=\"#dew\">DEW POINT<\/a><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t<div class=\"elementor-column elementor-col-33 elementor-top-column elementor-element elementor-element-62388b8\" data-id=\"62388b8\" data-element_type=\"column\" data-e-type=\"column\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t<div class=\"elementor-element elementor-element-09e18d8 elementor-widget elementor-widget-heading\" data-id=\"09e18d8\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><a href=\"#delta-t\">DELTA T<\/a><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t<section class=\"elementor-section elementor-top-section elementor-element elementor-element-c8e9f5c elementor-section-boxed elementor-section-height-default elementor-section-height-default\" data-id=\"c8e9f5c\" data-element_type=\"section\" data-e-type=\"section\">\n\t\t\t\t\t\t<div class=\"elementor-container elementor-column-gap-default\">\n\t\t\t\t\t<div class=\"elementor-column elementor-col-33 elementor-top-column elementor-element elementor-element-a4ec0f1\" data-id=\"a4ec0f1\" data-element_type=\"column\" data-e-type=\"column\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t<div class=\"elementor-element elementor-element-31a17ab elementor-widget elementor-widget-heading\" data-id=\"31a17ab\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><a href=\"#pore-ec\">PORE EC<\/a><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t<div class=\"elementor-column elementor-col-33 elementor-top-column elementor-element elementor-element-8361b82\" data-id=\"8361b82\" data-element_type=\"column\" data-e-type=\"column\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t<div class=\"elementor-element elementor-element-9f50a85 elementor-widget elementor-widget-heading\" data-id=\"9f50a85\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\"><a href=\"#evapotranspiration\">EVAPOTRANSPIRATION<\/a><\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t<div class=\"elementor-column elementor-col-33 elementor-top-column elementor-element elementor-element-ebdb6de\" data-id=\"ebdb6de\" data-element_type=\"column\" data-e-type=\"column\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t<div class=\"elementor-widget-wrap\">\n\t\t\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t<section class=\"elementor-section elementor-top-section elementor-element elementor-element-c07b983 elementor-section-boxed elementor-section-height-default elementor-section-height-default\" data-id=\"c07b983\" data-element_type=\"section\" data-e-type=\"section\">\n\t\t\t\t\t\t<div class=\"elementor-container elementor-column-gap-default\">\n\t\t\t\t\t<div class=\"elementor-column elementor-col-100 elementor-top-column elementor-element elementor-element-2ede99c\" data-id=\"2ede99c\" data-element_type=\"column\" data-e-type=\"column\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t<div class=\"elementor-element elementor-element-7a4e512 elementor-widget-divider--view-line elementor-widget elementor-widget-divider\" data-id=\"7a4e512\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"divider.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"elementor-divider\">\n\t\t\t<span class=\"elementor-divider-separator\">\n\t\t\t\t\t\t<\/span>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t<section class=\"elementor-section elementor-top-section elementor-element elementor-element-1d28938 elementor-section-boxed elementor-section-height-default elementor-section-height-default\" data-id=\"1d28938\" data-element_type=\"section\" data-e-type=\"section\">\n\t\t\t\t\t\t<div class=\"elementor-container elementor-column-gap-default\">\n\t\t\t\t\t<div class=\"elementor-column elementor-col-100 elementor-top-column elementor-element elementor-element-5a6ff70\" data-id=\"5a6ff70\" data-element_type=\"column\" data-e-type=\"column\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t<div class=\"elementor-element elementor-element-0690020 elementor-widget elementor-widget-menu-anchor\" data-id=\"0690020\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"menu-anchor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"elementor-menu-anchor\" id=\"vpd\"><\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-2ec8155 elementor-widget elementor-widget-heading\" data-id=\"2ec8155\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">VPD<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-cd0f9c7 elementor-widget elementor-widget-text-editor\" data-id=\"cd0f9c7\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<strong style=\"color: #333333; font-family: 'Open Sans Condensed'; font-size: 17px;\">1. INTRODUCTION<\/strong>\n<\/br><\/br>\n<strong>WHAT IS VAPOUR PRESSURE DEFICIT?<\/strong>\n<\/br><\/br>\nIf you have a METOS<sup>\u00ae<\/sup> device with hygroclip sensor (air temperature and relative humidity) now you can also see Vapour pressure deficit values and chart in <span style=\"text-decoration: underline;\"><a href=\"http:\/\/www.FieldClimate.com\">FieldClimate<\/a>.<\/span> Vapour pressure deficit (VPD) is a value calculated from relative humidity and air temperature and is in a close relationship to evapotranspiration.\n<\/br><\/br>\nVPD is an indication that takes into account the effect of temperatures on the water-holding capacity of the air, which is what drives transpiration of the leaf surface (transpiration occurs when water pressure in leaves is higher than air vapour pressure).\n<\/br><\/br>\nIt is the difference between the amount of moisture in the air and how much moisture the air can hold when it\u2018s saturated (100 % RH). When the air is saturated (vapour starts to condensate) the clouds will form, dew will form, and leaf wetness will appear.\n<\/br><\/br>\nIf we have <strong>low VPD<\/strong>, this means that <strong>RH<\/strong> is <strong>high<\/strong> and <strong>transpiration<\/strong> is <strong>low<\/strong>, we also have leaf wetness.\n<\/br><\/br>\nIf we have <strong>high VPD<\/strong>, this means that <strong>RH<\/strong> is <strong>low<\/strong>, no leaf wetness, and plants need to draw more water with its roots &#8211; <strong>high transpiration<\/strong>.\n<\/br><\/br>\n<img fetchpriority=\"high\" decoding=\"async\" src=\"https:\/\/www.metos.global\/wp-content\/uploads\/2022\/12\/vpd-table.jpg\" alt=\"VPD table\" width=\"521\" height=\"599\" \/>\n<\/br><\/br>\nTable 1: Vapour pressure (mBar) at various air temperatures (\u00b0C) and relative humidities (%).\n<\/br><\/br>\n<strong>WHAT IS NEEDED FOR CALCULATION?<\/strong><\/br>\n\u2022 Air temperature (from HC)<\/br>\n\u2022 Relative humidity (from HC)\n<\/br><\/br>\nWe can then calculate the saturation pressure. Saturation pressure can be looked up in a psychrometric chart or derived from the Arrhenius equation, a way to compute it directly from temperature is:\n<\/br><\/br>\n<img decoding=\"async\" data-src=\"\/wp-content\/uploads\/2022\/12\/vpd-chart.jpg\" alt=\"vpd-chart\" width=\"622\" height=\"456\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 622px; --smush-placeholder-aspect-ratio: 622\/456;\" \/>\n<\/br><\/br>\n<strong>Figure 1:<\/strong> Psychrometric chart\n<\/br><\/br>\n<strong>HOW IS IT SHOWN IN FieldClimate?<\/strong>\n<\/br><\/br>\n<img decoding=\"async\" data-src=\"\/wp-content\/uploads\/2022\/12\/VPD-graph.jpg\" alt=\"VPD graph in FieldClimate\" width=\"1575\" height=\"458\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 1575px; --smush-placeholder-aspect-ratio: 1575\/458;\" \/>\n<\/br><\/br>\n<strong>Figure 2:<\/strong> VPD Chart on FieldClimate showing vapour pressure deficit (mBar), air temperature (\u00b0C) and relative humidity (%).\n<\/br><\/br>\n&nbsp;\n<h4><strong>2. USE CASES<\/strong><\/h4>\n<strong>2.1 TOO HIGH VPD (humidity too low)<\/strong>\n<\/br><\/br>\nRate of evapotranspiration from the leaves can exceed the supply of water through the roots &#8211; the stomata will close and photosyntesis will slow down or stop. Leaves are at risk of high temperature injury, since evaporative cooling is reduced.\n<\/br><\/br>\nTo avoid injury and death from wilting, many plant species will either curl their leaves or orient them downwards in attempt to expose less surface area to the sun. This can downgrade the quality of potted and foliage plants and can also reduce the growth rate and quality of vegetable crops.\n<\/br><\/br>\n<img decoding=\"async\" data-src=\"\/wp-content\/uploads\/2022\/12\/vpd-ranges-rh-temp.jpg\" alt=\"vpd-ranges-rh-temp\" width=\"430\" height=\"361\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 430px; --smush-placeholder-aspect-ratio: 430\/361;\" \/>\n<\/br><\/br>\n<img decoding=\"async\" data-src=\"\/wp-content\/uploads\/2022\/12\/vpd-ranges.jpg\" alt=\"vpd-ranges\" width=\"388\" height=\"167\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 388px; --smush-placeholder-aspect-ratio: 388\/167;\" \/>\n<\/br><\/br>\n<strong>2.2 TOO LOW VPD (humidity too high)<\/strong>\n<ul>\n \t<li>Plants are unable to evaporate enough water to enable the transport of minerals (calcium) to growing plant cells, even that the stomata may be fully open.<\/li>\n \t<li>At extremly low VPD water may condens onto leaves, fruits and other plant parts. This can provide a medium for fungal growth and disease.<\/li>\n \t<li>At low VPD also gutation can occur (plant exude water from their leaf cells).<\/li>\n \t<li>When plants are unable to evaporate water, excessive turgor pressure within cells can cause splitting and cracking of fruits (for example tomato).<\/li>\n \t<li>In cases where VPD alternates between too high and too low, fruit quality can be adversely affected by shrink cracks in the skin of the fruit, as turgor pressure alternately expands and contracts the water-filled cells in the fruit.<\/li>\n<\/ul>\n<strong>\u00a0<\/strong>\n<\/br><\/br>\n<strong>2.3 USE OF VPD IN NURSERY<\/strong>\n<\/br><\/br>\n<strong>1.<\/strong> Newly rooted cutlings or just germinated seedlings or young plants, with limited foliage and a small root system. This plants should have low transpiration, so we need to keep them at low VPD (4 \u2013 8 mbar) in order to achive that high RH must be established (depending on temperature).\n<\/br><\/br>\n<strong>2.<\/strong> Good established plants, with developed foliage and root system. This plants should have higher VPD (8 \u2013 12 mbar), that means we need to keep low RH (depending on temperature), and that we have high transpiration. We achive with that:\n<ul>\n \t<li>More healthy plants, because of lower diseases pressure (low RH).<\/li>\n \t<li>More nutrients uptake, because of more root system activity (high transpiration), also more water uptake.<\/li>\n \t<li>If we keep high VPD at lower temperature (higher RH), we will avoid transpiration stress.<\/li>\n<\/ul>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t<section class=\"elementor-section elementor-top-section elementor-element elementor-element-64c5074 elementor-section-boxed elementor-section-height-default elementor-section-height-default\" data-id=\"64c5074\" data-element_type=\"section\" data-e-type=\"section\">\n\t\t\t\t\t\t<div class=\"elementor-container elementor-column-gap-default\">\n\t\t\t\t\t<div class=\"elementor-column elementor-col-100 elementor-top-column elementor-element elementor-element-7155275\" data-id=\"7155275\" data-element_type=\"column\" data-e-type=\"column\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t<div class=\"elementor-element elementor-element-bcfbd53 elementor-widget elementor-widget-menu-anchor\" data-id=\"bcfbd53\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"menu-anchor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"elementor-menu-anchor\" id=\"dew\"><\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-6dfb758 elementor-widget elementor-widget-heading\" data-id=\"6dfb758\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">DEW POINT<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-1ba4b8f elementor-widget elementor-widget-text-editor\" data-id=\"1ba4b8f\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<p>The dew point is the temperature at which air is saturated with water vapor. When air has reached the dew-point temperature at a particular pressure, the water vapor in the air is in equilibrium with liquid water, meaning water vapor is condensing at the same rate at which liquid water is evaporating.<\/p><p>Below the dew point, liquid water will begin to condense on solid surfaces (such as blades of grass) or around solid particles in the atmosphere (such as dust or salt), forming clouds or fog. If the relative humidity is 100%, the dew point temperature is the same as the air temperature. Thus the air is saturated. If the temperature decreases, but the amount of water vapour stays constant, water will start to condensate. This condensed water is called dew as soon as it forms on a solid surface. It is expressed in degrees Celsius (\u00b0C) as well as in degrees Fahrenheit (\u00b0F).<\/p><p><strong><em>Applications<\/em><\/strong><br \/>Dew point temperature can be used to predict when a\u00a0<strong>radiative frost<\/strong>\u00a0will take place. For example, if the skies are clear, winds are light, and the air temperature at 6 pm is 7.2 \u00b0C (45\u00b0F), but the dew point is -2.2\u00b0C (28\u00b0F), then there is a potential for killing frost. Again, this is the potential to which the temperature can drop to under ideal conditions, but most likely not the actual low temperature.<\/p><p>High dew points can be used as a\u00a0<strong>prediction of severe weather<\/strong>. The higher the dew point, the more moisture in the air for severe weather development. If dew points are below 13\u00b0C (55\u00b0F) conditions are generally\u00a0<strong>stable<\/strong>, if temperature are around 18\u00b0C (between 55 to 64\u00b0F) semi moist and\u00a0<strong>semi unstable<\/strong>, around 18\u00b0C (65 to 74\u00b0F) moist and\u00a0<strong>unstable<\/strong>\u00a0and above 23\u00b0C (74\u00b0F) very moist and\u00a0<strong>very unstable<\/strong>. There are a number of other factors required for severe weather, but dew point temperature is important factor.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t<section class=\"elementor-section elementor-top-section elementor-element elementor-element-9b37f89 elementor-section-boxed elementor-section-height-default elementor-section-height-default\" data-id=\"9b37f89\" data-element_type=\"section\" data-e-type=\"section\">\n\t\t\t\t\t\t<div class=\"elementor-container elementor-column-gap-default\">\n\t\t\t\t\t<div class=\"elementor-column elementor-col-100 elementor-top-column elementor-element elementor-element-460ee1f\" data-id=\"460ee1f\" data-element_type=\"column\" data-e-type=\"column\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t<div class=\"elementor-element elementor-element-db2aee2 elementor-widget elementor-widget-menu-anchor\" data-id=\"db2aee2\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"menu-anchor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"elementor-menu-anchor\" id=\"delta-t\"><\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-f791dbd elementor-widget elementor-widget-heading\" data-id=\"f791dbd\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">DELTA T<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-47bd91d elementor-widget elementor-widget-text-editor\" data-id=\"47bd91d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<p><a name=\"overview\"><\/a><\/p><h4><strong>1.OVERVIEW<\/strong><\/h4><p><strong>WHAT IS DELTA T?<\/strong><\/p><ul><li>Delta T calculation requires an hygroclip sensor (Air Temperature and Relative Humidity) installed on the METOS<sup>\u00ae<\/sup> station: data can be viewed on FieldClimate in charts and tables with a detailed resolution.<\/li><li>It is a measure that takes into account the combined effects of temperature and humidity and it indicates whether climatic conditions are suitable for spraying in order to maximize pesticide performance (A. MacGregor, 2010).<\/li><li>The optimal Delta T range is between 2\u00b0C and 8\u00b0C.<\/li><li>Although applicable all year round it is especially used in summer as higher temperatures and low relative humidity limit spraying time.<\/li><li>Keep monitoring Delta T reading and set up an efficient spray on schedule. Weather conditions can change rapidly during the day, so having the ability to monitor delta T can help to improve pesticide performance.<\/li><\/ul><p><img decoding=\"async\" class=\"wp-image-40727 size-medium aligncenter lazyload\" data-src=\"https:\/\/www.metos.global\/wp-content\/uploads\/2022\/04\/Pessl-Instruments-Hygroclip-300x244.png\" alt=\"Pessl Instruments Hygroclip (Air Temperature and Relative Humidity)\" width=\"300\" height=\"244\" data-srcset=\"https:\/\/metos.global\/wp-content\/uploads\/2022\/04\/Pessl-Instruments-Hygroclip-300x244.png 300w, https:\/\/metos.global\/wp-content\/uploads\/2022\/04\/Pessl-Instruments-Hygroclip.png 716w\" data-sizes=\"(max-width: 300px) 100vw, 300px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 300px; --smush-placeholder-aspect-ratio: 300\/244;\" \/><\/p><p><strong>Figure 1:<\/strong> Air Temperature and Relative Humidity Hygroclip sensor<\/p><p><a name=\"delta-t-calculations\"><\/a><\/p><h4><strong>2. DELTA T CALCULATIONS<\/strong><\/h4><h4>Sensors needed:<\/h4><ul><li>Air Temperature (from hygroclip)<\/li><li>Relative Humidity (from hygroclip)<\/li><\/ul><p>Delta T is calculated by subtracting the wet bulb temperature from the dry bulb temperature.<\/p><p><img decoding=\"async\" class=\"aligncenter wp-image-49932 lazyload\" data-src=\"https:\/\/www.metos.global\/wp-content\/uploads\/2022\/12\/Delta-T-calculations.png\" alt=\"Delta T calculations\" width=\"550\" height=\"484\" data-srcset=\"https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/Delta-T-calculations.png 770w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/Delta-T-calculations-300x264.png 300w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/Delta-T-calculations-768x676.png 768w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/Delta-T-calculations-14x12.png 14w\" data-sizes=\"(max-width: 550px) 100vw, 550px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 550px; --smush-placeholder-aspect-ratio: 550\/484;\" \/><\/p><p><strong>Figure 2:<\/strong> The relationship of Delta T to temperature and relative humidity. A common spray guideline is to spray when Delta T is between 2 and 8, with caution below 2 or above 10 (yellow areas). A Delta T value above 8\u00b0C is associated with higher temperatures and lower humidity, if lower than 2\u00b0C it is related to high relative humidity values. Source: Adapted by Gramae Tepper (2012) originally sourced from Nufarm\u2019s sprays decisions chart.<\/p><p><a name=\"delta-t-in-fieldclimate\"><\/a><\/p><h4><strong>3. DELTA T IN FIELDCLIMATE<\/strong><\/h4><p>Delta T is integrated in the <strong>Spraying Climate Window<\/strong>. It is available as a 7-day accurate forecast, calculated on an hourly basis and calibrated with on-side data from your METOS<sup>\u00ae<\/sup> station.<\/p><p><img decoding=\"async\" class=\"alignnone size-full wp-image-49934 lazyload\" data-src=\"\/wp-content\/uploads\/2022\/12\/FieldClimate-delta-t.jpg\" alt=\"FieldClimate-delta t\" width=\"1608\" height=\"464\" data-srcset=\"https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/FieldClimate-delta-t.jpg 1608w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/FieldClimate-delta-t-300x87.jpg 300w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/FieldClimate-delta-t-1024x295.jpg 1024w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/FieldClimate-delta-t-768x222.jpg 768w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/FieldClimate-delta-t-1536x443.jpg 1536w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/FieldClimate-delta-t-18x5.jpg 18w\" data-sizes=\"(max-width: 1608px) 100vw, 1608px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 1608px; --smush-placeholder-aspect-ratio: 1608\/464;\" \/><\/p><p><strong>Figure 3:<\/strong> Delta T trend in relation to Air Temperature and Relative Humidity in <span style=\"text-decoration: underline;\"><a href=\"http:\/\/www.fieldclimate.com\/\">FieldClimate<\/a>.<\/span><\/p><p><a name=\"how-to-use-it\"><\/a><\/p><h4><strong>4. HOW TO USE IT<\/strong><\/h4><p>On-site weather condition readings are required before each spray, in particular a live reading of Delta T is always recommended.<\/p><ul><li>Set a minimum or maximum threshold for SMS warning. Delta T live reading is updated every 5 minutes.<\/li><li>For a more effective spray application combine Delta T with more weather parameters, e.g. wind speed and direction: avoid either variable or gusty or too calm wind conditions.<\/li><\/ul><p><img decoding=\"async\" class=\"alignnone size-full wp-image-49935 lazyload\" data-src=\"\/wp-content\/uploads\/2022\/12\/use-delta-t.jpg\" alt=\"\" width=\"1393\" height=\"579\" data-srcset=\"https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/use-delta-t.jpg 1393w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/use-delta-t-300x125.jpg 300w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/use-delta-t-1024x426.jpg 1024w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/use-delta-t-768x319.jpg 768w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/use-delta-t-18x7.jpg 18w\" data-sizes=\"(max-width: 1393px) 100vw, 1393px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 1393px; --smush-placeholder-aspect-ratio: 1393\/579;\" \/><\/p><p><strong>Figure 4:<\/strong> Insert Delta T marginal values in FieldClimate.<\/p><p><strong><a>TOO LOW DELTA T<\/a><\/strong><\/p><ul><li>Droplet survival will be very long leading to increased potential for drift \u2013 avoid spraying with RH&gt;95%.<\/li><li>Spray will not run off the leaf because of dew or fog.<\/li><li>Avoid spraying during calm wind conditions \u2013 inversion layer therefore drifts.<\/li><\/ul><p><strong><a>TOO HIGH DELTA T<\/a><\/strong><\/p><ul><li>Avoid values greater than 10\u00b0C.<\/li><li>Avoid spraying in air temperatures above 28\u00b0C.<\/li><li>Potential impact on both droplet survival and evaporation rate: spray droplet will evaporate off the plant leaf before it has time to enter the plant tissue.<\/li><li>Stressful situations for applying herbicides.<\/li><\/ul>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t<section class=\"elementor-section elementor-top-section elementor-element elementor-element-d205af1 elementor-section-boxed elementor-section-height-default elementor-section-height-default\" data-id=\"d205af1\" data-element_type=\"section\" data-e-type=\"section\">\n\t\t\t\t\t\t<div class=\"elementor-container elementor-column-gap-default\">\n\t\t\t\t\t<div class=\"elementor-column elementor-col-100 elementor-top-column elementor-element elementor-element-15ba5c9\" data-id=\"15ba5c9\" data-element_type=\"column\" data-e-type=\"column\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t<div class=\"elementor-element elementor-element-bcc9518 elementor-widget elementor-widget-menu-anchor\" data-id=\"bcc9518\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"menu-anchor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"elementor-menu-anchor\" id=\"pore-ec\"><\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5ed35da elementor-widget elementor-widget-heading\" data-id=\"5ed35da\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">PORE EC<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5306f92 elementor-widget elementor-widget-text-editor\" data-id=\"5306f92\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<p>For the Decagon 5TE sensor it is now possible to calculate in FieldClimate the Pore EC according to the method illustrated in the <em>5TE Operators. Manual Version 3 \u2013 Decagon<\/em>, derived form Hilhorst, M.A. 2000. To activate the calculation you have to switch it on in the <em>Soil moisture configuration<\/em> tool as indicated in Fig. 1. The calculation requires an offset term, which Decagon recommends to set equal to 6. This is also the default value inserted in FieldClimate, but it\u2019s possible to change it in the relative box indicated in Fig. 1, since Hilhorst applies for different soils and media values between 1,9 and 7,6 and suggest to use an average value of 4,1.<\/p><p><img decoding=\"async\" class=\"size-full wp-image-49942 aligncenter lazyload\" data-src=\"\/wp-content\/uploads\/2022\/12\/pore-ec.png\" alt=\"\" width=\"625\" height=\"214\" data-srcset=\"https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/pore-ec.png 625w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/pore-ec-300x103.png 300w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/pore-ec-18x6.png 18w\" data-sizes=\"(max-width: 625px) 100vw, 625px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 625px; --smush-placeholder-aspect-ratio: 625\/214;\" \/><\/p><p><strong>Figure 1<\/strong> \u2013 Only for Decagon 5TE sensor: activation of the pore EC calculation and offset term setting.<\/p><p><strong>IMPORTANT NOTE:<\/strong><\/p><ul><li>Remember that Bulk EC, Pore EC and Solution EC are different variables.<\/li><li>The applied model cannot be used in dry soil. As a rule of thumb, the model applies for most normal soils and other substrates, if VWC &gt; 10% . In any case the calculation is valid only with bulk permittivity bigger than the offset term.<\/li><\/ul>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t<section class=\"elementor-section elementor-top-section elementor-element elementor-element-6e1b814 elementor-section-boxed elementor-section-height-default elementor-section-height-default\" data-id=\"6e1b814\" data-element_type=\"section\" data-e-type=\"section\">\n\t\t\t\t\t\t<div class=\"elementor-container elementor-column-gap-default\">\n\t\t\t\t\t<div class=\"elementor-column elementor-col-100 elementor-top-column elementor-element elementor-element-ba636a8\" data-id=\"ba636a8\" data-element_type=\"column\" data-e-type=\"column\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t<div class=\"elementor-element elementor-element-a34794e elementor-widget elementor-widget-menu-anchor\" data-id=\"a34794e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"menu-anchor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"elementor-menu-anchor\" id=\"evapotranspiration\"><\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-1bf9f80 elementor-widget elementor-widget-heading\" data-id=\"1bf9f80\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">EVAPOTRANSPIRATION<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d19f3cd elementor-widget elementor-widget-text-editor\" data-id=\"d19f3cd\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<p>ET0 daily evapotranspiration is calculated with the FAO-56 Penman-Monteith equation and needs measurements (sensors) of:<\/p><ul><li>Air temperature<\/li><li>Air humidity<\/li><li>Solar radiation<\/li><li>Wind speed<\/li><\/ul><p>ET0 lets us know how much water the plant requires to grow each day, based on atmospheric demand. This water comes from root zone soil moisture and\/or precipitation. On a typical hot day, a corn crop can use 7 to 9 mm or about 1\/3 of an inch of water. In a week that could by 30 to 50 mm of water. This allow us to plan how much potential water is required to maintain crop health and yield.<\/p><p><img decoding=\"async\" class=\"size-full wp-image-49949 aligncenter lazyload\" data-src=\"\/wp-content\/uploads\/2022\/12\/ET-daily-evapotranspiration.jpg\" alt=\"ET-daily-evapotranspiration\" width=\"1024\" height=\"511\" data-srcset=\"https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/ET-daily-evapotranspiration.jpg 1024w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/ET-daily-evapotranspiration-300x150.jpg 300w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/ET-daily-evapotranspiration-768x383.jpg 768w, https:\/\/metos.global\/wp-content\/uploads\/2022\/12\/ET-daily-evapotranspiration-18x9.jpg 18w\" data-sizes=\"(max-width: 1024px) 100vw, 1024px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 1024px; --smush-placeholder-aspect-ratio: 1024\/511;\" \/><\/p><p>Another Method to assess the evapotranspiration rates is the use of evapotranspiration pans.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"<p>VIRTUAL SENSORS VAPOUR PRESSURE DEFICIT DEW POINT DELTA T PORE EC EVAPOTRANSPIRATION VPD 1. INTRODUCTION WHAT IS VAPOUR PRESSURE DEFICIT? If you have a METOS\u00ae device with hygroclip sensor (air temperature and relative humidity) now you can also see Vapour pressure deficit values and chart in FieldClimate. Vapour pressure deficit (VPD) is a value calculated [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"elementor_header_footer","meta":{"ocean_post_layout":"","ocean_both_sidebars_style":"","ocean_both_sidebars_content_width":0,"ocean_both_sidebars_sidebars_width":0,"ocean_sidebar":"0","ocean_second_sidebar":"0","ocean_disable_margins":"enable","ocean_add_body_class":"","ocean_shortcode_before_top_bar":"","ocean_shortcode_after_top_bar":"","ocean_shortcode_before_header":"","ocean_shortcode_after_header":"","ocean_has_shortcode":"","ocean_shortcode_after_title":"","ocean_shortcode_before_footer_widgets":"","ocean_shortcode_after_footer_widgets":"","ocean_shortcode_before_footer_bottom":"","ocean_shortcode_after_footer_bottom":"","ocean_display_top_bar":"default","ocean_display_header":"default","ocean_header_style":"","ocean_center_header_left_menu":"0","ocean_custom_header_template":"0","ocean_custom_logo":0,"ocean_custom_retina_logo":0,"ocean_custom_logo_max_width":0,"ocean_custom_logo_tablet_max_width":0,"ocean_custom_logo_mobile_max_width":0,"ocean_custom_logo_max_height":0,"ocean_custom_logo_tablet_max_height":0,"ocean_custom_logo_mobile_max_height":0,"ocean_header_custom_menu":"0","ocean_menu_typo_font_family":"0","ocean_menu_typo_font_subset":"","ocean_menu_typo_font_size":0,"ocean_menu_typo_font_size_tablet":0,"ocean_menu_typo_font_size_mobile":0,"ocean_menu_typo_font_size_unit":"px","ocean_menu_typo_font_weight":"","ocean_menu_typo_font_weight_tablet":"","ocean_menu_typo_font_weight_mobile":"","ocean_menu_typo_transform":"","ocean_menu_typo_transform_tablet":"","ocean_menu_typo_transform_mobile":"","ocean_menu_typo_line_height":0,"ocean_menu_typo_line_height_tablet":0,"ocean_menu_typo_line_height_mobile":0,"ocean_menu_typo_line_height_unit":"","ocean_menu_typo_spacing":0,"ocean_menu_typo_spacing_tablet":0,"ocean_menu_typo_spacing_mobile":0,"ocean_menu_typo_spacing_unit":"","ocean_menu_link_color":"","ocean_menu_link_color_hover":"","ocean_menu_link_color_active":"","ocean_menu_link_background":"","ocean_menu_link_hover_background":"","ocean_menu_link_active_background":"","ocean_menu_social_links_bg":"","ocean_menu_social_hover_links_bg":"","ocean_menu_social_links_color":"","ocean_menu_social_hover_links_color":"","ocean_disable_title":"on","ocean_disable_heading":"default","ocean_post_title":"","ocean_post_subheading":"","ocean_post_title_style":"","ocean_post_title_background_color":"","ocean_post_title_background":0,"ocean_post_title_bg_image_position":"","ocean_post_title_bg_image_attachment":"","ocean_post_title_bg_image_repeat":"","ocean_post_title_bg_image_size":"","ocean_post_title_height":0,"ocean_post_title_bg_overlay":0.5,"ocean_post_title_bg_overlay_color":"","ocean_disable_breadcrumbs":"default","ocean_breadcrumbs_color":"","ocean_breadcrumbs_separator_color":"","ocean_breadcrumbs_links_color":"","ocean_breadcrumbs_links_hover_color":"","ocean_display_footer_widgets":"default","ocean_display_footer_bottom":"default","ocean_custom_footer_template":"0","footnotes":""},"class_list":["post-49909","page","type-page","status-publish","hentry","entry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.6 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Virtual sensors - METOS by Pessl Instruments<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/metos.global\/en\/virtual-sensors\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Virtual sensors - METOS by Pessl Instruments\" \/>\n<meta property=\"og:description\" content=\"VIRTUAL SENSORS VAPOUR PRESSURE DEFICIT DEW POINT DELTA T PORE EC EVAPOTRANSPIRATION VPD 1. 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