OT - Question about sub-zero weather

[Big B]

For those of you who live in Canada, or Minnesota, - or any other area that routinely gets serious sub-zero weather every winter...

If the sun is out in the daytime (with no cloud cover) on a freezing day (say -35 degrees F), will the temperature likely drop much more at night?
I'm from southern California and I really have no idea about temperature changes in those conditions, but I was exposed to them once - and I have always been curious as to whether it gets much colder at night in sub-zero weather?

Just curious.

B

[bradfordkay]

Typically, in winter clear weather is cold weather. You hit on part of it right off... the cloud cover helps keep some warmth near the surface but the other part is that clear weather is usually a sign of a high pressure system associated with a cold front. SO, yes, in clear weather the night time temperatures will usually drop substantially lower than they would on a cloudy night. 

[Big B]

REALLY??? The temp would actually drop noticeably at night?? What would you guess - maybe drop 10 degrees or more?

Jeeze that would explain a few things I always wondered about.
Thanks!

ORIGINAL: bradfordkay

Typically, in winter clear weather is cold weather. You hit on part of it right off... the cloud cover helps keep some warmth near the surface but the other part is that clear weather is usually a sign of a high pressure system associated with a cold front. SO, yes, in clear weather the night time temperatures will usually drop substantially lower than they would on a cloudy night. 

[Ghertz]

There will be a significant temperature drop at night because no clouds will be available to reflect radiation back to the earth's surface.

[Big B]

Well, the reason I asked was because 30 years ago I was an infantryman in the Cal Army N.G. . And in January 1981, when Ronald Reagan was 1st sworn in as president, we were doing our 15 days A.T. at Ft. Ripley Minnesota for cold weather training.
We loaded aboard C-130's from Los Alamitos NAS, and it was about 74 degrees when we left California, but six hours later when we landed in St. Paul Minn. it was down to 4 degrees. A day or so later we went out to the field and set up our tents for the remainder of our time there.
The only time I saw a thermometer out in the field was one day on an M-60 MG range - inside a squad sized tent (with a little stove) and the thermometer in there read -35 degrees F (inside the tent). There was very little snow at the time (the entire time we were there - that made the mandatory cross-country skiing difficult), and mostly clear skies.
Anyway, one night, while sleeping in our sleeping bags on the frozen ground, I got so cold I literally couldn't breath - so - only wearing my skivvies, I jumped up and started running around (in panic) trying to force air in my lungs. I was really cold, and to
this day - I always wondered if the temp actually dropped below -35?
Overall, I thought Minnesota was a nice place - but you shouldn't camp outside there during the winter.

[rjopel]

-35 at Camp Ripley in the winter.

So it was a pretty nice day then.

[Big B]

Well I said was a sunny day[:D]

One other interesting thing I saw there - they had a nicely restored M-4A-3E2 Sherman Jumbo there on post, only had the 75mm gun though.

ORIGINAL: rjopel

-35 at Camp Ripley in the winter.

So it was a pretty nice day then.

[John Lansford]

Clear nights in winter always result in lower temperatures than the daytime temps, because the heat radiates away and there's nothing to keep it closer to the ground.  Snowcovered ground is even worse, because the snow reflects sunlight away from the ground so there's even less heat to radiate away.

[frank1970]

Don´t know too much about American winters [;)], but here in good old Germany (Grafenwöhr, some of you might know), it gets substantial colder in the night, when there is no cloud cover.
I´d say the temperature difference might easily be 30°C. So a "warm day with 5°C with sun might get a very cold night with -25 to -30°C or colder.

[Big B]

Just to show you some old photos, here are some 30 year old snaps of that trip.
Me in the top photo, Our squad Sgt Joe Wright adjusting field gear below.

B

ORIGINAL: Frank

Don´t know too much about American winters [;)], but here in good old Germany (Grafenwöhr, some of you might know), it gets substantial colder in the night, when there is no cloud cover.
I´d say the temperature difference might easily be 30°C. So a "warm day with 5°C with sun might get a very cold night with -25 to -30°C or colder.

[Big B]

And another
Me with my M-60 on top, Jim Hartsell, our Platoon's comedian in the drivers seat of the M113 below.

[sventhebold]

Well to answer your question yes it gets COLD here. I used to live on the farm in northern Minn and we had an interesting geography. The house sat in the bottom of a small valley with trees around it so it did not get really windy there. BUT in there lies the rub. When an intense high moves in from up north the barometer can go up near 31.55 or higher and the airmass flows like molasses across the continent. It pools in the lowest places and our place was near perfect. After a fresh snowfall there is no heat near the ground at all. The last winter on the farm 1980-81 was exceptional as Jan- Feb is was dancing around -35 to -45 or so and warming up to -15 during the day. It was 15 Feb and I had gone out to the barn to check on the animals around 6am (1 horse, 15 sheep, 3 geese) to fill water tanks (hand carry 5 gallon pails) and to make sure the horse tank (with electric heater moved around) stayed open. I wore two layers of long johns and three layers of clothing. As the sun came up finally I could read the tempature and it read -52 degrees. I called it in to the weather service in Fargo. But the really strange part was on 30 March 45 days later we had a record high of 100 degrees! The ground was still frozen out in the woods and mid sized trees were exploding! The sap was trying to run and the roots were still frozen and every so often you would hear a crack or a bang out in the woods as trees split open or physically blew apart.

[sventhebold]

Come to think of it one of the worst problems I had was working on equipment in the cold and my wrists would be exposed to the cold metal and ocasionally had bloody wrists from tearing frozen skin off on the metal.

[fflaguna]

Nice pictures! What was your job in the service?

[Big B]

Thanks, I was an 11 Bravo (11-B-10) - basic infantryman. My first job with my company was M-203 gunner for my squad, then, being only 5'7" and 145 pounds they gave me the M-60 to carry.
After a while, I got to be a track driver and got out of a lot of humping around on foot (back then a track was an M-113 APC), then finally I got to be the designated jeep driver for our platoon's LT (very cushy position - more to my liking).[:D]

ORIGINAL: fflaguna

Nice pictures! What was your job in the service?

Well sventhebold, I can certify that that particular January was a cold one in Minn.
I never knew if that was unusual until now.... shiver.

ORIGINAL: sventhebold

Well to answer your question yes it gets COLD here. I used to live on the farm in northern Minn and we had an interesting geography. The house sat in the bottom of a small valley with trees around it so it did not get really windy there. BUT in there lies the rub. When an intense high moves in from up north the barometer can go up near 31.55 or higher and the airmass flows like molasses across the continent. It pools in the lowest places and our place was near perfect. After a fresh snowfall there is no heat near the ground at all. The last winter on the farm 1980-81 was exceptional as Jan- Feb is was dancing around -35 to -45 or so and warming up to -15 during the day. It was 15 Feb and I had gone out to the barn to check on the animals around 6am (1 horse, 15 sheep, 3 geese) to fill water tanks (hand carry 5 gallon pails) and to make sure the horse tank (with electric heater moved around) stayed open. I wore two layers of long johns and three layers of clothing. As the sun came up finally I could read the tempature and it read -52 degrees. I called it in to the weather service in Fargo. But the really strange part was on 30 March 45 days later we had a record high of 100 degrees! The ground was still frozen out in the woods and mid sized trees were exploding! The sap was trying to run and the roots were still frozen and every so often you would hear a crack or a bang out in the woods as trees split open or physically blew apart.

ORIGINAL: sventhebold

Come to think of it one of the worst problems I had was working on equipment in the cold and my wrists would be exposed to the cold metal and ocasionally had bloody wrists from tearing frozen skin off on the metal.

[JohnDillworth]

Makes a difference that it is inland. I live in the Northeast US very near the ocean. Even in dead winter there will rarely be more than a 20 degree difference. Even in dead winter the ocean tend to hold the heat, what there is of it at least.

[stevemk1a]

It gets pretty cold up here in the winter, down to about -40C or so at times. During a cold snap, the coldest part of the day is always just after the sun comes up in the morning (I'm not really sure why though). We get some pretty wild fluctuations in temperature ... last weekend it was -30C and this weekend it's +5C.

Driving to work on a cold morning, the first few meters it feels like your tires are square!

[Mundy]

Being a Wisconsonite, we typically see the freeze.  Especially when I used to live up in Superior, going to school.
 
Up there in Jan, I remember week to 10 day stretches of 15-20 (F) below.  Nights would usually hit -25 to -30 when that happened.  I won't even get into wind chill, since it was always windy there.  Before I learned the wisdom of the engine block heater, the car would just quit after a few days of this.  When it would get back up to zero, it felt like a heat wave.
 
There was this town in northern MN, called Tower.  They always seemed 10 degrees colder than anyone else around.
 
M-

[stevemk1a]

Before I learned the wisdom of the engine block heater

True enough! Anything below -30C and you need to plug in. Some Honda's have an oil-pan heater instead and it's just not anywhere near as good ... a battery warmer is also handy. Funnily enough, my crappy old '99 Sunfire will start on the first crank every time even without being plugged in, but my wife's newer car needs to be warmed with a block heater first. Let's hear it for low compression and less gadgets [:D]

[Chickenboy]

ORIGINAL: bradfordkay

Typically, in winter clear weather is cold weather. You hit on part of it right off... the cloud cover helps keep some warmth near the surface but the other part is that clear weather is usually a sign of a high pressure system associated with a cold front. SO, yes, in clear weather the night time temperatures will usually drop substantially lower than they would on a cloudy night. 

+1

Interesting that in Minnesota at least, it usually snows in the 20s-30s. Rarely do we got snow at -10 or so.