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Old 08-07-2011, 03:54 PM
 
Location: San Luis | Argentina
45 posts, read 100,436 times
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USA TODAY.

The amount of humidity in the air by itself doesn't make any difference in how cold the air "feels." Sometimes you will hear that the water vapor in the air carries heat away, cooling you faster. At first glance that might seem to make sense because most people have heard of victims of boating accidents dying because they weren't pulled from chilly water before dying of hypothermia -- a cooling of the body's core temperature. In these cases the water does quickly carry heat away from the body and people with no protection can die quickly in 40-degree water. But, even on the most humid of days, especially when the air is chilly, the percentage of water molecules in the air as water vapor is very small. Even if water molecules did carry heat away from your body, there are too few to noticeably cool you. Also, it turns out that water vapor molecules are no better at conducting heat than the nitrogen and oxygen molecules that make up most of the air.
What I have to say here is based on the "Water Vapor Mysticism" chapter in a delightful book, What Light Through Yonder Window Breaks: More Experiments in Atmospheric Physics by Craig F. Bohren, published by John Wiley & Sons, Inc. in 1991. In it, he not only gives the theoretical arguments in the paragraph above, but also describes some simple, home experiments to show things don't cool faster in cool but humid air than in cool but dry air.
Why do people think wet cold is more uncomfortable than dry cold? Bohren's answer makes sense to me. Humid places are often cloudy. A cold, sunny day doesn't feel as chilly as a cold, cloudy day because even as the air is cooling us, direct sunlight is warming us. The USATODAY.com
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Old 08-07-2011, 04:20 PM
 
Location: Destrehan, Louisiana
2,189 posts, read 7,052,824 times
Reputation: 3637
Quote:
Originally Posted by Tequeño View Post
USA TODAY.

The amount of humidity in the air by itself doesn't make any difference in how cold the air "feels." Sometimes you will hear that the water vapor in the air carries heat away, cooling you faster. At first glance that might seem to make sense because most people have heard of victims of boating accidents dying because they weren't pulled from chilly water before dying of hypothermia -- a cooling of the body's core temperature. In these cases the water does quickly carry heat away from the body and people with no protection can die quickly in 40-degree water. But, even on the most humid of days, especially when the air is chilly, the percentage of water molecules in the air as water vapor is very small. Even if water molecules did carry heat away from your body, there are too few to noticeably cool you. Also, it turns out that water vapor molecules are no better at conducting heat than the nitrogen and oxygen molecules that make up most of the air.
What I have to say here is based on the "Water Vapor Mysticism" chapter in a delightful book, What Light Through Yonder Window Breaks: More Experiments in Atmospheric Physics by Craig F. Bohren, published by John Wiley & Sons, Inc. in 1991. In it, he not only gives the theoretical arguments in the paragraph above, but also describes some simple, home experiments to show things don't cool faster in cool but humid air than in cool but dry air.
Why do people think wet cold is more uncomfortable than dry cold? Bohren's answer makes sense to me. Humid places are often cloudy. A cold, sunny day doesn't feel as chilly as a cold, cloudy day because even as the air is cooling us, direct sunlight is warming us. The USATODAY.com

People who step off an plain from California to New Orleans will beg to differ with ya.

busta
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Old 08-07-2011, 05:24 PM
 
1,344 posts, read 1,743,517 times
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Why then did -5F in upstate NY feel the same as 25F did in CT just 1 week apart. In both cases there was no windchill and the sky was clear. Additionally i didn't do anything (exercise, drink hot water, etc) that would drastically alter my core temp.

Anyone?
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Old 08-07-2011, 05:30 PM
 
Location: Free From The Oppressive State
30,253 posts, read 23,737,137 times
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Hmm. I would like this to be true but have to agree with the above poster.

In Florida, the temps may be 89 degrees, same as you might find in sunny California, but I guarantee you that you're going to feel a whole lot hotter in FL.

So, does the reverse hold true for cold? Well, in eastern WA it's very dry. In western WA while not extremely humid, is more humid than eastern WA. In eastern WA we could get away with a long sleeve shirt and sweatshirt and jeans in the winter. In western WA we were bundled up, freezing, the cold going to the bone, it felt like. Same temps.

I'm not here to argue with a scientist, I go only on what I actually feel because facts schmacts, doesn't matter if I feel colder.
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Old 08-07-2011, 10:20 PM
 
645 posts, read 1,276,056 times
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My first year out of the Marine Corps saw huge changes for me. Immediately out of the Suck, I landed an average job, but I couldn’t afford reliable transportation. By the way, this was 1986. To make a long story short, which I’m bad at doing, I continued my job search, and at the end of the first year, I landed a job in a factory, where I doubled my wage.

The new job was further away, and I went through a lot of cars. I also had a girlfriend, and I made significantly more money than her, so we largely depended on my income alone. Hence, she got a newer car, and I soldiered on with an old wreck that was the same age as me. The car died. I didn’t have the time to change engines and all that folly, so I just broke down and bought a brand new motorcycle.

In the second full year out of the Corps, I rode motorcycle 25 miles each way to work. I did this year round. There were days when it was –05 Fahrenheit. This was my experience. I would rather ride a motorcycle in 20-degree weather in my home state because 20-degree weather is typically very dry. A lot of people complain about chapped skin and lips when the weather’s like this. I favored dry 20 degree-days over 35 – 40 degrees accompanied by very damp weather. The reason was simple, the cold dry air did not cut through my leather in the same fashion that the warmer, but still cold damp air did. I know that defies logic, but the problem is, once you understand how the human body perceives relative temperature, you’ll understand completely why humid weather always feels different than dry weather. For example

Humid cold/hot weather will always feel colder/hotter
Dry cold/hot weather will always feel warmer/cooler

Get the idea? I hope this helped.
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Old 08-08-2011, 02:02 AM
 
Location: Buxton, England
6,990 posts, read 11,416,855 times
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From my experiences this winter the coldest I felt was when it was humid and damp with temps above freezing.

I coped with the cold better when it was well below freezing with low relative humidity as well, even at night (with no sun to make it feel warmer).

Reason? Because when the air is saturated, it is more conductive against my skin. In the cold, at high humidity, I can feel the water particles against my skin and I lose my body heat into the air much quicker.
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Old 08-08-2011, 04:51 AM
 
Location: Perth, Western Australia
9,589 posts, read 27,808,501 times
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^^ yes, they are ignoring the factor of condensation.

It's like calling BS on someone getting colder because it started to rain and they got wet.
100% humidity without rain isn't nearly as bad as getting soaked in rain, but it is noticeable.
Even above 85% you can find microclimates cold enough there is condensation.

I would say for humidity at 75% and below, I agree with the original point.
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Old 08-08-2011, 05:10 AM
 
Location: San Luis | Argentina
45 posts, read 100,436 times
Reputation: 46
Quote:
Originally Posted by Weatherfan2 View Post
From my experiences this winter the coldest I felt was when it was humid and damp with temps above freezing.

I coped with the cold better when it was well below freezing with low relative humidity as well, even at night (with no sun to make it feel warmer).

Reason? Because when the air is saturated, it is more conductive against my skin. In the cold, at high humidity, I can feel the water particles against my skin and I lose my body heat into the air much quicker.
thats just your opinion, not scientific truth.
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Old 08-08-2011, 05:17 AM
 
Location: Buxton, England
6,990 posts, read 11,416,855 times
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Quote:
Originally Posted by Tequeño View Post
thats just your opinion, not scientific truth.
False.

When I feel myself getting colder quicker in damp cold weather, it isn't my "opinion", it is what is happening. My body loses heat faster in those conditions. Then it takes longer to warm up again. I think I KNOW how cold/warm my body is.
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Old 08-08-2011, 05:29 AM
 
Location: Perth, Western Australia
9,589 posts, read 27,808,501 times
Reputation: 3647
Quote:
Originally Posted by Tequeño View Post
thats just your opinion, not scientific truth.
Go stand outside when it's 4 C and dry and wait for it to be 4 C and raining.
If you do not feel colder as you get wet, I will be very impressed.
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