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Mountain Weather
10/04/2002
Listen in RealAudio 
Hi, I'm Bryan Yeaton and this is The Weather Notebook. Let me set the scene for today's
weather commentator and self-described weather die-hard, David Laskin. It's summer, the Laskin
brood is taking a road trip through high elevation country and as David notes,the familiar
question arises.
No matter how many times my family and I drive over mile high Washington Pass in the North
Cascade Mountains we never cease to be amazed by how much colder it is than Seattle.
"I don't get it", one of my daughters piped up as our minivan cruised between walls of snow
that had lingered into June. "We're 5000 feet closer to the sun up here plus warm air rises,
right? So, what's with all the snow?"
Ah, nothing like a meteorological discussion to warm the heart of a weather fanatic father.
The answer in a word is pressure. As you ascend into the mountains air pressure decreases
because there's less pressure overhead weighing down on you. And the air molecules themselves
are farther apart and moving more slowly. The higher you climb the lower the pressure and the
lower the pressure the colder the air. The rate of temperature loss is about 3.5 degrees
Fahrenheit for every thousand feet of elevation gained.
I used to think my father was crazy when he talked about mountain weather, but now I realize
that he was on to something. Considering that Earth's atmosphere is hundreds of miles high
it's amazing what impact even a modest mountain can have on weather.
David Laskin makes his observations from his home post in Seattle, Washington. David is the
author of numerous books, some on weather that you can find on our website at
weathernotebook.org. Speaking of The Weather Notebook, it's a production of the Mount
Washington Observatory and is supported by Subaru and the National Science Foundation.
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