Re: OT: Really dumb question on atmospheric conditions
It's quite simple. Water vapor - H2O molecules in a gaseous state - are what causes light to scatter. The colder the air, the less water vapor it can contain. Therefore there is less scattering of light resulting in a clearer view. At 01:02 PM 12/3/2002 -0500, you wrote: It was about 9 degrees Fahrenheit this morning and very clear out. It seems it is usually or often clear when very cold. Dumb question but is this some kind of rule: is it always/usually clearer when cold? And why? Is it because of the cold, or some other related factor which may be present when it is not cold or may sometimes not be present when it is cold)? Or is it all in my imagination? Thanks and forgive my ignorance... Gary J Sibio [EMAIL PROTECTED] http://home.earthlink.net/~garysibio/ Time flies like an arrow. Fruit flies like bananas.
Re: OT: Really dumb question on atmospheric conditions
Forgot to add that dry air seems more "clear" since it contains less water droplets to diffract the light. Steven Desjardins Department of Chemistry Washington and Lee University Lexington, VA 24450 (540) 458-8873 FAX: (540) 458-8878 [EMAIL PROTECTED] >>> [EMAIL PROTECTED] 12/03/02 01:21PM >>> The vapor pressure of water goes up with temperature, so there is a tendency to have less humidity (more water in the liquid state) in colder conditions. Of course, the atmosphere is such a massively non-equilibrium system that its hard to apply simple thermodynamic arguments. Deserts are dry with heat for the a similar reason with an opposite result, i.e., the water goes into the air and blows away. It depends a lot on how close you are to the water and how the jet stream brings moisture to you. Steven Desjardins Department of Chemistry Washington and Lee University Lexington, VA 24450 (540) 458-8873 FAX: (540) 458-8878 [EMAIL PROTECTED] >>> [EMAIL PROTECTED] 12/03/02 01:02PM >>> It was about 9 degrees Fahrenheit this morning and very clear out. It seems it is usually or often clear when very cold. Dumb question but is this some kind of rule: is it always/usually clearer when cold? And why? Is it because of the cold, or some other related factor which may be present when it is not cold or may sometimes not be present when it is cold)? Or is it all in my imagination? Thanks and forgive my ignorance... Rob _ MSN 8 with e-mail virus protection service: 2 months FREE* http://join.msn.com/?page=features/virus
Re: OT: Really dumb question on atmospheric conditions
Robert Soames Wetmore wrote: > > It was about 9 degrees Fahrenheit this morning and very clear out. It seems > it is usually or often clear when very cold. Dumb question but is this some > kind of rule: is it always/usually clearer when cold? And why? Is it > because of the cold, or some other related factor which may be present when > it is not cold or may sometimes not be present when it is cold)? Or is it > all in my imagination? Thanks and forgive my ignorance... > > Rob How about this? With no cloud cover (nessary condition for MY explanation) all things exposed to the sky are exposed to something like 4 degrees Kelvin. Not far from absolute zero. Any heat in things on earth are radiating toward the much colder temperature of the sky. This is why tender exposed leaves on plants can freeze solid, when out door temps are recording 50 degrees, if there's no wind, and all the plant 'sees' is the clear night sky. That's why those tending the plants frequently cover the small plants with small tents on clear nights. To keep them from freezing! That's my contribution... keith whaley
Re: OT: Really dumb question on atmospheric conditions
Rob, Weather is the result of air having a different ability to carry moisture at different temperatures. Water dissolves into air, and hot air can carry/absorbe a lot more water. When this warm air gets cold, the moisture has to go somewhere... into rain or snow or Fog. And then it falls on you. Big masses of cold and warm air fight it out across the landscape. Where they collide is often a string of thunderstorms or snow. When the cold air wins and displaces the warm stuff, it often becomes clear and dry (and obviously cold). This is often a great time to get some shots in sunshine. We had lake effect snow here this AM. Same principle, warm air over Lake Michigan pick up moisture. Prevailing winds blow the air over the colder land. Air gets cold and drops its moisture as snow. Winds have now changed and I'm looking at a snowy landscape in bright sunshine! Regards, Bob S. [EMAIL PROTECTED] writes: > It was about 9 degrees Fahrenheit this morning and very clear out. It seems > it is usually or often clear when very cold. Dumb question but is this some > kind of rule: is it always/usually clearer when cold? And why? Is it > because of the cold, or some other related factor which may be present when > it is not cold or may sometimes not be present when it is > cold)? Or is it > all in my imagination? Thanks and forgive my ignorance... > > Rob
Re: OT: Really dumb question on atmospheric conditions
The vapor pressure of water goes up with temperature, so there is a tendency to have less humidity (more water in the liquid state) in colder conditions. Of course, the atmosphere is such a massively non-equilibrium system that its hard to apply simple thermodynamic arguments. Deserts are dry with heat for the a similar reason with an opposite result, i.e., the water goes into the air and blows away. It depends a lot on how close you are to the water and how the jet stream brings moisture to you. Steven Desjardins Department of Chemistry Washington and Lee University Lexington, VA 24450 (540) 458-8873 FAX: (540) 458-8878 [EMAIL PROTECTED] >>> [EMAIL PROTECTED] 12/03/02 01:02PM >>> It was about 9 degrees Fahrenheit this morning and very clear out. It seems it is usually or often clear when very cold. Dumb question but is this some kind of rule: is it always/usually clearer when cold? And why? Is it because of the cold, or some other related factor which may be present when it is not cold or may sometimes not be present when it is cold)? Or is it all in my imagination? Thanks and forgive my ignorance... Rob _ MSN 8 with e-mail virus protection service: 2 months FREE* http://join.msn.com/?page=features/virus
OT: Really dumb question on atmospheric conditions
It was about 9 degrees Fahrenheit this morning and very clear out. It seems it is usually or often clear when very cold. Dumb question but is this some kind of rule: is it always/usually clearer when cold? And why? Is it because of the cold, or some other related factor which may be present when it is not cold or may sometimes not be present when it is cold)? Or is it all in my imagination? Thanks and forgive my ignorance... Rob _ MSN 8 with e-mail virus protection service: 2 months FREE* http://join.msn.com/?page=features/virus
