Am I full of hot air?
December 7, 2009 7:00 PM Subscribe
Help me settle a bet. Does the air temperature affect how windy it is?
For instance, if it is really cold, say like below 10 degrees F, would that make it be less windy out?
Thanks!
For instance, if it is really cold, say like below 10 degrees F, would that make it be less windy out?
Thanks!
For instance, if it is really cold, say like below 10 degrees F, would that make it be less windy out?
Thanks!
I found the question really hard to answer as stated, but I'm giving it a go.
Air temperatures, or temperature gradients, can affect wind conditions, that's what the weather people are talking about with cold fronts and low pressure zones etc, but cold air isn't somehow less able to move in response to pressure than warm air. There are many very cold places that are often very windy.
posted by pseudonick at 7:11 PM on December 7, 2009
Air temperatures, or temperature gradients, can affect wind conditions, that's what the weather people are talking about with cold fronts and low pressure zones etc, but cold air isn't somehow less able to move in response to pressure than warm air. There are many very cold places that are often very windy.
posted by pseudonick at 7:11 PM on December 7, 2009
Ack. floam is totally right about there being temperature dependent viscosity changes, so it should take more energy to get cold air moving, though in practical terms I don't think it is likely to be significant compared to the forces that are driving wind speeds.
Of course if you get cold enough you'll solidify the atmosphere which would really reduce wind speeds.
posted by pseudonick at 7:26 PM on December 7, 2009
Of course if you get cold enough you'll solidify the atmosphere which would really reduce wind speeds.
posted by pseudonick at 7:26 PM on December 7, 2009
Three weeks ago in Alaska: Low of -45 and high of -35. 186MPH winds.
posted by puritycontrol at 7:34 PM on December 7, 2009
posted by puritycontrol at 7:34 PM on December 7, 2009
if it is really cold, say like below 10 degrees F, would that make it be less windy out?
No.
Wind is caused by pressure gradients. The steeper the pressure gradient, the stronger the wind. There is, in general, no particular correlation between pressure gradient and temperature.
posted by flabdablet at 8:05 PM on December 7, 2009
No.
Wind is caused by pressure gradients. The steeper the pressure gradient, the stronger the wind. There is, in general, no particular correlation between pressure gradient and temperature.
posted by flabdablet at 8:05 PM on December 7, 2009
I would also expect that denser air would feel windier for a given MPH than less dense air. In other words, you feel the extra energy it takes to make the heavier air move.
Another thing that might be confusing the original issue is that when it is really cold out (for the given season), you are usually at the center of a high pressure zone. When it is warmer, you are usually in a low pressure zone, or in an area of a front moving in. So subjectively, it would seem less windy when it seems cold out.
(There may be something about being in an area that the wind is moving out of versus into. But that's a thought-puzzle I can't parse right now.)
posted by gjc at 8:21 PM on December 7, 2009
Another thing that might be confusing the original issue is that when it is really cold out (for the given season), you are usually at the center of a high pressure zone. When it is warmer, you are usually in a low pressure zone, or in an area of a front moving in. So subjectively, it would seem less windy when it seems cold out.
(There may be something about being in an area that the wind is moving out of versus into. But that's a thought-puzzle I can't parse right now.)
posted by gjc at 8:21 PM on December 7, 2009
On preview, what flabdablet said --wind is a product of the pressure gradient.
The flip side of puritycontrol's example is a hurricane, which is going to have tropical temperatures and, well, hurricane force winds.
posted by plastic_animals at 8:21 PM on December 7, 2009
The flip side of puritycontrol's example is a hurricane, which is going to have tropical temperatures and, well, hurricane force winds.
posted by plastic_animals at 8:21 PM on December 7, 2009
Antarctica is one of the windiest places on Earth and is also one of the coldest. Ditto for Siberia.
And Aruba and Hawaii are known for their constant winds and are both warmer than either Antarctica or Siberia.
So...
posted by dfriedman at 8:30 PM on December 7, 2009
And Aruba and Hawaii are known for their constant winds and are both warmer than either Antarctica or Siberia.
So...
posted by dfriedman at 8:30 PM on December 7, 2009
Does the air temperature affect how windy it is?
It's more the other way around. At night, heat is lost at the surface due to the longwave radiation coming off from the ground. This creates a temperature inversion, where the temperature actually increases with height. Strong winds will keep the lower atmosphere well mixed and impede the formation of the inversion. So when winds are light or calm (often under high pressure like gjc stated), it can get colder than on a similar night with wind.
Of course, it is often more complicated than that. Nighttime low temperatures are also impacted by cloud cover (clear skies = outgoing radiation escapes to space = colder surface temps), if there is snow or not, and if there is cold air advection. This is when the winds are actually bringing in colder temperatures from somewhere else, and is usually strongest behind a cold front. But in general, on a cold night it is not less windy because of the temperatures, but it is 10 F because it is less windy.
posted by weathergal at 8:47 PM on December 7, 2009
It's more the other way around. At night, heat is lost at the surface due to the longwave radiation coming off from the ground. This creates a temperature inversion, where the temperature actually increases with height. Strong winds will keep the lower atmosphere well mixed and impede the formation of the inversion. So when winds are light or calm (often under high pressure like gjc stated), it can get colder than on a similar night with wind.
Of course, it is often more complicated than that. Nighttime low temperatures are also impacted by cloud cover (clear skies = outgoing radiation escapes to space = colder surface temps), if there is snow or not, and if there is cold air advection. This is when the winds are actually bringing in colder temperatures from somewhere else, and is usually strongest behind a cold front. But in general, on a cold night it is not less windy because of the temperatures, but it is 10 F because it is less windy.
posted by weathergal at 8:47 PM on December 7, 2009
Others have already answered the question, so I won't rehash it.
I will, however recommend Bill Bryson's book, A Short History of Nearly Everything, which not only spends a chapter explaining the weather, but also explains a whole pile of other phenomena. It's a very accessible book, and perfect for anyone who has a desire to dabble in all fields of science.
posted by swngnmonk at 9:15 PM on December 7, 2009
I will, however recommend Bill Bryson's book, A Short History of Nearly Everything, which not only spends a chapter explaining the weather, but also explains a whole pile of other phenomena. It's a very accessible book, and perfect for anyone who has a desire to dabble in all fields of science.
posted by swngnmonk at 9:15 PM on December 7, 2009
Could somebody address the *perception* of wind with different temperatures? We calculate wind chill, why not "wind burn"?
posted by msittig at 9:31 PM on December 7, 2009
posted by msittig at 9:31 PM on December 7, 2009
Since hot air rises, isn't warmer air windier than cooler air? Meaning yes, that all things being equal, warmer air is windier than cooler air. Its just moving in the skyward direction?
posted by Taurid at 10:19 PM on December 7, 2009
posted by Taurid at 10:19 PM on December 7, 2009
Since hot air rises, isn't warmer air windier than cooler air? Meaning yes, that all things being equal, warmer air is windier than cooler air. Its just moving in the skyward direction?
It's not necessarily more windy, it's more turbulent. If a load of warm air is stuck under cold air, you get thunderstorms, tornadoes, what have you. It's not that warm air is more likely to move across the landscape (make wind), it's that it's trying to create an equilibrium and that involves moving all the air on the ground to the upper atmosphere.
posted by fiercekitten at 11:55 PM on December 7, 2009
It's not necessarily more windy, it's more turbulent. If a load of warm air is stuck under cold air, you get thunderstorms, tornadoes, what have you. It's not that warm air is more likely to move across the landscape (make wind), it's that it's trying to create an equilibrium and that involves moving all the air on the ground to the upper atmosphere.
posted by fiercekitten at 11:55 PM on December 7, 2009
Since hot air rises, isn't warmer air windier than cooler air? Meaning yes, that all things being equal, warmer air is windier than cooler air. Its just moving in the skyward direction?
By that logic, you could say that cold air is equally windy as it is "falling" in a groundward direction.
posted by qwip at 1:18 AM on December 8, 2009
By that logic, you could say that cold air is equally windy as it is "falling" in a groundward direction.
posted by qwip at 1:18 AM on December 8, 2009
To follow on from dfriedman, one of the reasons that cold Antarctica and warm Hawaii are windy is surface roughness. The water around Hawaii and ice of Antarctica are very smooth compared to any type of land, so your wind shear is completely different.
posted by scruss at 4:54 AM on December 8, 2009 [1 favorite]
posted by scruss at 4:54 AM on December 8, 2009 [1 favorite]
Three weeks ago in Alaska: Low of -45 and high of -35. 186MPH winds.
The plural of anecdote is not data
posted by chrisamiller at 7:49 AM on December 8, 2009 [1 favorite]
The plural of anecdote is not data
posted by chrisamiller at 7:49 AM on December 8, 2009 [1 favorite]
msittig writes "Could somebody address the *perception* of wind with different temperatures? We calculate wind chill, why not 'wind burn'?"
Moving air never feels warmer than still air. Even at 40C any wind blowing on exposed skin will feel cooler than still air. It's also why the wind chill at 300 Km/h isn't significantly different than the wind chill at a 100 Km/h; your skin is only able to transfer so much energy to the wind.
posted by Mitheral at 3:44 PM on December 8, 2009
Moving air never feels warmer than still air. Even at 40C any wind blowing on exposed skin will feel cooler than still air. It's also why the wind chill at 300 Km/h isn't significantly different than the wind chill at a 100 Km/h; your skin is only able to transfer so much energy to the wind.
posted by Mitheral at 3:44 PM on December 8, 2009
This thread is closed to new comments.
posted by Paragon at 7:04 PM on December 7, 2009