Dear Straight Dope:
I have at least one thing in common with Cecil -- people are always
asking me questions on everything. If it is useless information, there is a good chance I will know the answer. If it is useful information they are seeking, I tell them I have a meeting to go to and can't be bothered right now. Today I was asked, "Why is there snow on mountains in the summer?" and I rattled off some babble about altitude and pressure, not actually knowing what I was talking about. Could you possibly help me enlighten my clueless co-workers on the meteorological reasons?
I think we’ll make a great team, Skinman: I’ll send all of the questions we get which require “useless information” your way, and you can send me all of the questions with answers in the “useful information” category. Ooops, I guess we’re already crossing boundaries here …
The answer to your question is quite simple, and I’m sure if you hadn’t actually had a meeting to go to you would have come up with it. The reason that there is snow on mountains in the summer is that it hasn’t melted yet.
But perhaps you wanted to know why. Several factors go into the speed with which the snow will melt. You were correct in some of your babble: as you go higher, the temperature decreases. This is due to the fact that the earth stores heat from the sun, and the higher you go, the less earth there is around you. Obviously, the colder it is, the more time it will take for the snow to melt. The next factor is
the sun: it has a bit of a warming effect, so even if the outside temperature is 32 degrees Fahrenheit, the surface snow will be wanting to melt because the sun is beating down on it. The next factor is the volume of snow: the more there is, the longer it will take to melt, because the snow underneath the surface will have a cooling effect on the surface which is counteracting the warming effect of the sun and air. This is easily demonstrable in
your own backyard: put a one-pound block of ice next to an ice-cube on your patio on a warm summer day and see which melts first. There’s also something known as “adiabatic cooling,” but Cecil took a pass on this one the one time it came up, and I strive always to emulate The Boss.
Send questions to Cecil via email@example.com.
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