2006-10-24 22:25:51 · 9 answers · asked by JV 1 in Environment
The saturation partial vapour pressure of water is very much lower at low temperatures (cold air can only hold very much less moisture).
2006-10-24 22:33:00 · answer #1 · answered by Robert A 5 · 0⤊ 0⤋
because cold air can have less water in suspension in it. To simplify, just imagine, the molecules in cold air move less, so anything that is not gas will have a higher chance to "fall down" (i.e. condensate). Whereas in hot air, where molecules vibrate more, the prevent that condensation from happening.
what makes it tricky, though, is that in weather forecasting, people use "percentage humidity", and this is a RELATIVE measure, with 100% corresponding to where water would condensate. But since hot air can contain more water, 99% humidity in hot air means much more water, in mass per unit volume of air, than 99% humitidy in cold air.
So what's weird is that, looking at reported weather observation, you may well see 90% humidity on a hot summer day, and still 90% humidity on a cold winter day - but these will be very different, in terms of how much water is actually in the air (much less in a cold day).
hope this helps, rather than confuses...
2006-10-25 06:42:29 · answer #2 · answered by AntoineBachmann 5 · 0⤊ 0⤋
Cold air usually looses a lot of its mositure due to condensation. Hence you tend to get warm moist air and cold dry air. However, in places like the Sahara the air can be very hot and still be very dry.
2006-10-25 08:13:25 · answer #3 · answered by uselessadvice 4 · 0⤊ 0⤋
When air gets cold, the water vapour it carries condenses and gets convered to dew and leaves the air dry.
2006-10-25 05:30:37 · answer #4 · answered by slender 2 · 0⤊ 0⤋
Because it is dry. When water vapor cools down it becomes dew, then frost. Which means it is no longer in the air. Think of it like putting jello in the fridge. Only nothing like that.
2006-10-25 05:34:28 · answer #5 · answered by cat_Rett_98 4 · 0⤊ 0⤋
becaule the colder the air the less moisture it can sustain.....humidty levels decrease the colder the air mass.
2006-10-25 05:28:28 · answer #6 · answered by Tragedy 3 · 0⤊ 0⤋
because it usually lack moisture, hence the dryness, and the chapping of the lips and such
2006-10-25 05:27:13 · answer #7 · answered by chance m 2 · 0⤊ 0⤋
Then where do we get snow from ? Import it ?
2006-10-25 05:34:56 · answer #8 · answered by Anonymous · 0⤊ 0⤋
...................... moisture becomes dew........... at a certain temp ........ called dew point .............. and air is free of moisture ..........
2006-10-25 05:29:58 · answer #9 · answered by spaceman 5 · 0⤊ 0⤋