Tuesday, December 16, 2008

I don't get it.

How come if I sit on the porch and it's 25 degrees out, I freeze my butt off, but if I sit on the porch and it's 25 degrees and snowing, it feels fine?

Weird.

17 comments:

og said...

Dunno, but I've noticed that too.

Weer'd Beard said...

Not sure if there can be humidity durring snow, but moisture in the air will make it feel warmer.

Also windchill will also be a factor for sensation of cold

jimbob86 said...

You are distracted by the purty white stuff? "Show 'em sumpin' shiny........"

Anonymous said...

You've never heard of a "blanket of snow"?

OldeForce

Jason said...

{incomming wall of text}

There is less humidity in the air when its snowing than when it isn't...

Humidity in the air helps to transfer temperatures (as water is an outstanding thermal regulator). In warmer than body temperature air (i.e. 99*+ F) the humidity in the air actually tries to increase the temperature of your skin and cool the air in contact (the 120* air tries to regulate towards 98.6* of your body, and vice versa). Unfortunately, theres a lot more hot sweltering air than there is relatively cool bodies, thus the bodies heat up. Sweat is produced to help lower the body's temperature.

Conversely, in the winter, the air is actually relatively free of ambient moisture when it snows, as all the moisture/humidity is either settling as frost or falling as snow/ice. Therefore, there is very little moisture in the air to conduct heat away from your body, and the body is more easily able to regulate its temperature.

For a kitchen experiment, take two breasts of chicken, frozen solid. Put them in identical glass bowls. Leave one on the counter, and place the other one under slowly trickling cold water. The one under cold water (easily 40*F) will thaw MUCH faster than the one in room temperature (60*-70*F) air, because of the thermal movement caused by the water. In fact (non-seq), running frozen stuff under cold water is one of the best ways to thaw it, in fact, it works better than dropping it in boiling water (less energy is wasted equalizing water and object temperatures).

Or something along those lines. I used to watch Mr. Wizard a lot.. :/

JD said...

Sure it has nothing to do with the fact that sitting watching the snow fall leads to wanting a nice warm drink to go with it and a fire in the fire place and presto. . . . you are warm. . .

Just a thought. . .

Then again it could just be that humidity stuff Jason said. . .

DirtCrashr said...

That's what I hate about snow, it's never *here* - it's away up on the hills, so us down in the valley by the Bay are super-chilled like in a freakin' ice bath.

OrangeNeckInNY said...

The water vapor in the air, in its act of turning into snow, warms up the cold air around it (because heat transfers from hot to cold). So it may be 25 degrees. but will feel like 32 degrees.

Did you know that water exists as a liquid, solid and gas simultaneously at 0 deg. C?

Tam said...

Gee, Mr. Wizard! :D

(We don't have none o' them foreign metric degrees 'round these parts in flyover country. Just the good wholesome 'Murrican Fahrenheit kind.)

kbarrett said...

Orangeneck: Not quite correct.

Water's triple point is at 0.01C, and only at near vacuum: 0.006+ atmospheres.

theirritablearchitect said...

If I may simplify, somewhat; Water changing phase will transfer LOTS of energy, thereby releasing that energy to the atmosphere as the water vapor freezes to snow, making it feel warmer.

atlharp said...

Whatever the reason we all know it's George Bush's fault......

Anonymous said...

"If I may simplify, somewhat; Water changing phase will transfer LOTS of energy, thereby releasing that energy to the atmosphere as the water vapor freezes to snow, making it feel warmer."

Which is why during many snow storms it actually gets warmer as time. All teh condensation is releasing heat.

Of course if the reason things are condensating is massive high pressure front sweeping down from the north the the couple of degrees of warmth caused by condensation of the water is drowned in the fact that the air is dropping 30 degrees overall.

So you southerner's enjoying your Global Warming yet?

DirtCrashr said...

Unless the snow is falling where you are it's freakin' freezing. When it's falling way up yonder on all the hills that are surrounding you and the cold air rolls down the hills and crashes into you at the bottom it can crack ribs.
I'd rather be in Hawaii.

OrangeNeckInNY said...

It's warmer when it snows because hell froze over and has released all it exothermic energy into the air in Tam's vicinity. In Fahrenheit thermal measuring units.

I know it was 0.01*C for water to exist in all 3 states. I wasn't trying to be THAT specific. If I did, I would have given it using the Kelvin temperature scale.

And didn't I already say that heat transfers from hot to cold? And in doing so, imply that the water vapor in the air, which we all can figure out, is warmer than the surrounding air and would release its heat energy into said surrounding air? And as a result, crystalize and become snow?

Geez...:::shaking my head and feigning indignation:::

Okay, I'm tossing away my shovel. I'm not going to dig any further. Because I just concluded that Hell just froze over and it's cold down there. Besides, I don't want to run into PB...

heh...

Blackwing1 said...

I vote for none of the above.

Generally when it's snowing, it's cloudy. Even on a sunny day, if you're not in the direct sunshine, the upper atmosphere is at a very low temperature. You're essentially radiating heat away from your exterior surfaces (coat, sweater) to the upper atmosphere. Radiation heat transfer is a function of the difference in (absolute) temperatures to the fourth power (times factors referred to as "emissiviity" and the Stephen-Boltzman constant).

When it's snowing the clouds act like a huge radiation blanket, isolating your surfaces from the upper atmosphere's lower temperature.

This effect is strongest at night. On a clear night, even with the air temperature well above freezing you can get frost on surfaces, because they're radiating more heat to space through radiation than they're picking up through convective heat transfer from the (slightly) warmer air. This can lower their surface temperatures to below the freezing point, causing frost to form.

That's why orange groves use smoke pots (to try to artificially create that "blanket") or humongous fans (to artificially increase the convective heat transfer coefficient from the air to the oranges) to try to prevent frost/freezing.

OrangeNeckInNY said...

Or maybe it's because they're giving the oranges a "frost" so they naturally change from green to orange. Without a frost, oranges will remain green, even though they're ripe. Sometimes, when there's no frost, green oranges are artificially sprayed orange.