2007-06-10 15:34:02 · 5 answers · asked by kaavoolaa 2 in Science & Mathematics ➔ Weather
On a clear calm night, the atmosphere is stable. Heat energy is able to rise above the surface while the cooler and denser air will sink to near the surface. As this process continues through the night, the air just above the ground surface may cool to the point where some of the moisture a form of a gas will start to condense or change to a liquid form. This liquid that forms near the ground and is usually found on plants like grass or plant leaves are what we call dew.
If there is some wind, the wind can mix the warmer air from above back down towards the surface. If there are clouds, some of the heat energy will get absorbed by the clouds. The clouds can also radiate energy back towards the ground. In both of these cases, the ground surface will not cool as fast or as efficiently as if there was no wind and/or clouds in the sky during the night hours.
2007-06-11 11:18:21 · answer #1 · answered by UALog 7 · 0⤊ 0⤋
A combination of the right humidity and temperature reaches something called "dew point." Air contains water in suspension, its ability to hold that water is proportional to the air's temperature. As the temperature falls, air's ability to hold water in suspension weakens until is reaches "dew point" and the water falls out of suspension. That fall out is your dew on the ground.
As you might suspect, the ability to hold water in suspension also depends on just how much water is in suspension. Air is like a bucket, it can hold only so much water. If the bucket is filled to over the brim, it spills out. If air is filled to the brim, it spills out as rain, fog, dew, and such simply because there is more water than the container (the air) can hold.
Specifically, the dew forms on the ground during clear calm summer nights because the air, during the day, took on a lot of water due to evaporation. Thus, the humidity is high. At night time, when there are no clouds to hold the heat in, the air cools by radiation and when the temperature/humidity combination reaches dew point...out pops the dew. (or ground fog, or fog over a pond, or other things like that)
2007-06-10 15:50:13 · answer #2 · answered by oldprof 7 · 0⤊ 0⤋
as the air cools at night it no longer has the ability to hold as much water so it condenses it out causing the dew on the ground
2016-05-17 05:27:34 · answer #3 · answered by luann 3 · 0⤊ 0⤋
dew forms because the humidity in the air
2007-06-14 01:17:03 · answer #4 · answered by Janni 1 · 0⤊ 0⤋
cool air....warm ground makes the moisture in the air condense on the grass or plants or whatever is there.
2007-06-10 15:42:03 · answer #5 · answered by Gordon S 5 · 0⤊ 0⤋