📘 How does dew form on grass

What you’ll learn

1. A cool blade meets humid airExplain how surface cooling and the dew point turn water vapor into liquid droplets on grass.Dew begins at a boundary: a grass blade cools until the nearby vapor can no longer remain entirely gaseous.
2. Why grass is a good dew collectorIdentify why grass, clear skies, calm air, and nearby moisture make dew more likely.Grass loses heat readily, but clouds, wind, dry soil, and shelter can change whether the surface crosses its threshold.
3. Dew is not rain, fog, or frostDistinguish surface condensation from precipitation, suspended fog, freezing deposition, and plant guttation.The location and temperature of formation tell you whether morning moisture is dew, rain, fog, frost, or a bead the plant pushed out.

Questions this course answers

Grounded in trusted sources

• UCAR Center for Science Education — humidity, dew point, and why grass can be wet on a morning with no rain: https://scied.ucar.edu/learning-zone/how-weather-works/humidity
• NOAA National Weather Service — glossary definition of dew as moisture condensed on objects near the ground whose temperatures have fallen below the dewpoint: https://forecast.weather.gov/glossary.php?word=dew
• NWS Charleston — dew on clear, calm, moist nights with a low dew-point depression; frost by deposition or frozen dew; official air temperature measured about five feet up: https://www.weather.gov/rlx/frost-freeze-information
• NWS Houston training (Jeff Haby) — dew favored by clear skies, light wind, soil moisture, and a small dew-point depression: https://www.weather.gov/source/zhu/ZHU_Training_Page/fog_stuff/Dew_Frost/Dew_Frost.htm
• Met Office — grass and car surfaces cool faster than roads under clear skies; frost when the surface is below freezing and below the dew point: https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/business/sectors/how-does-frost-form.pdf
• University of Missouri IPM (Christopher J. Starbuck) — guttation as water exuded from hydathodes at leaf tips and margins, often mistaken for dew: https://ipm.missouri.edu/MEG/2009/6/Guttation-A-Pressure-Relief-for-Plants/index.cfm

Every Wunder lesson is built from real, reputable sources — never invented.

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