What is the relationship between altitude gain and temperature decrease when mountaineering?
In the absence of inversions, going up mountains will bring you into lower temperatures as you get higher.
What is the rule of thumb for how the temperature decreases with altitude?
1 answer
The answer is that it depends on the moisture held in the air
- moist air changes at a rate of 3° Fahrenheit per 1000 ft of vertical / 0.6° Celsius per 100m.
- dry air changes at a rate of 5.4° Fahrenheit per 1000 ft of vertical / 1° Celsius per 100m.
As moist air rises, it cools with height at a rate of 3°F per 1,000 feet (not nearly as fast as the dry-air rate of 5.4°F per 1,000 feet). Eventually clouds develop, and precipitation wrings moisture from the air. At the summit, the air is now both warmer and drier than air of the same altitude that has not climbed the mountain. But as the air passes over the summit and flows down the other side of the mountain, it compresses and warms at 5.4°F per 1,000 feet (now following the dry-air rate), creating a much warmer, dryer wind.
Discover Nature in the Weather: Things to Know and Things to Do
In Freedom of the Hills , they use an estimate of 3.5° Farenheit /2 ° Celsius per thousand feet to estimate the freezing level.
The idea is that if you know your elevation, the elevation you are going to and the temperature where you are, then you can use those pieces of information to estimate the temperature at the elevation you are headed to.
For instance, if base camp is at 11,000 ft and the peak is at 13,000 ft, then it will be approximately 7° Farenheit / 4° Celsius colder at the peak. This could be useful for calculating whether the snow will be frozen on the way up.
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