Editor's Note: OnTheSnow will feature a special question and answer section focusing weather starting today and extending each day through the end of January. OnTheSnow will take a question from a reader and present it to Colorado-based meteorologist Joel Gratz and post his answer on Facebook and OnTheSnow.com. Do you have a burning question you've always wanted to ask? Just post it in a comment here or on our Facebook page and we'll toss your name into the hat.
How does elevation affect temperature? Is there a simple way to estimate the summit temperature if I know the temperature at the base?
- Mr. Mears
Whistler, British Columbia
Like a lot of things in meteorology it’s fair to say you can “kind of” estimate the summit temperature by recording the temperature at the mountain’s base.
But before we get into numbers, it’s important to remember the temperature can vary for a number of different reasons.
Shade, sun, nearby buildings (or lack of them) and inversions (colder air sinking into valleys because it’s heaver than warm air) can all influence the temperature.
These caveats aside, here’s the scoop on temperature and elevation. If there is NO snow (or the dreaded rain) falling from the sky and you’re NOT in a cloud, then the temperature decreases by about 5.4 degrees Fahrenheit for every 1,000 feet up you go in elevation. In mathematical speak that is 9.8 degrees Celsius per 1,000 meters.
However, if you’re in a cloud, or it is snowing/raining, the temperature decreases by about 3.3 degrees Fahrenheit for every 1,000 feet up you go in elevation. Thus meaning it’s a change of 6 degrees Celsius per 1,0000 meters.)
I know. So here’s a handy chart to visualize the temperature decrease with elevation:
And now for the nerdy science part (you know you have some nerd in you!)
Atmospheric pressure is simply the weight of the air pushing down on you from above. As you increase in elevation, there is less air above you thus the pressure decreases. As the pressure decreases, air molecules spread out further (i.e. air expands) and the temperature decreases. If the humidity is at 100% (because it’s snowing!), the temperature decreases more slowly with height.
Perhaps best to left to another Q&A session.
So let’s put all this theory to the work. Say you wake up in Vail and it’s snowing hard. If the temperature at the base is 20F and the summit is about 3,000ft higher, then you could estimate the temperature at the top would be about 10F (3,000ft elevation change * 3.3F per 1,000ft, or 3 * 3.3 = about 10F temperature decrease).
Or perhaps you’re at the top of Whistler on a sunny but very cold day with temperatures around 5F at the top. It’s early afternoon and while it was cold when you started the day at the base, you’re now thinking it would be fun to head to the bottom to have a beverage and sit in the sun. But will it be warm enough down there? Of course!
Since it’s about 5,000ft between the summit and the base of Whistler, the temperature at the base village should be about 27F warmer than at the top (5,000ft elevation change * 5.4F per 1,000ft, or 5 * 5.4 = about 27F temperature increase). So the temperature at the base should be around 32F, and in the sun after a nice day on the hill, this is the scientifically perfect temperature to enjoy an outdoor beverage.
So Mr. Mears, you can now act as an amateur meteorologist and be a hero among your friends by estimating temperatures all over the mountain. Just remember that temperature changes 5.4F/1,000ft (9.8C/1,000m) if it’s dry and 3.3F/1,000ft (6C/1,000m) if it’s snowing.
Enjoy your time on the hill!
Meteorologist Joel Gratz, is the creator of www.ColoradoPowderForecast.com and is based in Boulder, Colorado.