Estimating Temperature @ Altitude??

[Ducky 0]

Just curious if there was a formula for estimating temperature at altitude based on the temperature on the ground???

I was considering doing some Hop n Pops from about 12k or so and was wondering how cool it would be and what to wear etc.


kwak

Sometimes your the bug, sometimes your the windshield. Sometimes your the hammer sometimes your the nail. Question is Hun, Do you wanna get hammered or do you wanna get nailed?????

[quade 3]

Yes there is. Unfortunately it can be wildly inaccurate since the moisture content of the air can vary so much.

Dry air has an adiabatic laspe rate of about 5.4°F per 1000 feet. That is to say that dry air will be cooler by about 5.4 for every 1000 feet increase of altitude.

The moist or saturated adiabatic lapse rate is approximately 2.0°F per 1000 feet.

As a rough average you can use 3.3°F per 1000 feet.

Further, some areas of the country, especially coastal regions can have an inversion layer. An inversion layer is caused by somewhat cooler air wedging its way under a warmer layer of air.

This happens frequently in southern California. The air over the desert warms up and rises. Cool air from the ocean blows in to replace it and gets trapped under the warm air. This is why you can see the air so well in southern California. Most people mistake this for smog, but in reality what they're mostly looking at is tiny salt particles in the air. Over the course of a few days however, this cooler layer of air does trap quite a bit of smog and since it's cooler than the air above it, it doesn't rise and dissipate, so, uh, yeah, it's smoggy.

This is also the main cause of what we call "June Gloom" in the SoCal area. The lower layer of air is cool and moist, so, that means foggy and low clouds. When the Sun comes up and warms the air somewhat, it "burns off".

Generally speaking, under the inversion layer is bumpy and above the inversion layer is pretty smooth air. You'll definately see the difference.

quade -
The World's Most Boring Skydiver

[Hooknswoop 19]

You can get temperatures aloft here:

http://adds.aviationweather.gov/winds/

The standard lapse rate is 3.5-degrees Fahrenheit /2-degrees Celsius for every 1000 feet. In other words the temperature drops 3.5-degrees Fahrenheit /2-degrees Celsius for every 1000 feet on a standard day. This is a good rule of thumb, but will vary day-to-day.

If it is 80-degrees Fahrenheit on the ground, it will be around 38-degrees Fahrenheit at 12,000 feet.

Hook

[darkvapor 0]

You can try this: http://www.grc.nasa.gov/WWW/K-12/airplane/atmos.html

Not sure how accurate that is for altitudes we are working with.

Under the "international standard atmosphere" sea level temperature is 59F, and drops 3.5°F per thousand feet.

Jumping at SD Atlanta, I've been doing hop'n'pops and CRW jumps lately, and I have not had any problems with temperature (wearing t-shirt, long pants, and gloves). In fact, it is quite comfortable for me. On the other hand, my hands were incredibly numb when I tried to do the same thing in December. During the Geogia summer months, I wouldn't worry about it. I've easily gone up with shorts and a t-shirt and didn't notice the cold.

[councilman24 36]

In Georgia, in summer? Wear as little as possible! Your not up there that long.

Seriously, it isn't much of a concern. Your fingers might get chilly and the last one I did my toes were cold in my sandles. But I want to shed as much heat as possible when it's going to be 90 when I land. On colder days, usually what your wearing to keep warm in freefall is enough. Don't forget to let go of your toggles and lower your arms to get the blood flowing in your hands.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[Amazon 7]

I have always figured roughly what I was taught in the USAF 30 years ago... 3 degrees per thousand. It usually holds true to a point.

I have seen days with inversions... especially here in the west when its FAR colder in the valley than it is at even 10k.

Other than that..........nipples.

Amazon

[champu 1]

it's funny being in florida where people shiver at altitude if they are anywhere near the door.

I jumped once up north in february, even with layers and two pairs of gloves I was numb and bordering on nauseous when I got back to the ground, needless to say I only did one jump that day

at altitude here the air is really nice =)

[kallend 1,621]

Ask the pilot. The plane will have an outside air temperature probe. Actual temperatures can be wildly different from "standard".

Also an aviation winds-aloft forecast will give predicted temperatures at 3, 6, 9, 12k

If you know a glider pilot, they often use the temperature profile to compute likely thermal activity.

...

The only sure way to survive a canopy collision is not to have one.

[tbrown 26]

I jumped once up north in february, even with layers and two pairs of gloves I was numb and bordering on nauseous when I got back to the ground, needless to say I only did one jump that day

[Ducky 0]

Shweet guys tanks for all the info. I plan o doing some playing up high tomorrow and now I am better prepared.


kwak

Sometimes your the bug, sometimes your the windshield. Sometimes your the hammer sometimes your the nail. Question is Hun, Do you wanna get hammered or do you wanna get nailed?????