MOUNTAIN AIR: Mountain air is very different than what you may be used to. It is thin and dry. There is simply less air to breathe than you may be accustomed to and the relative humidity is low. The low humidity has several negative effects that your body may not be accustomed to. The dry air creates some extreme temperature variations. It’s common for night time lows to be in the teens and daytime highs to be in the 60s. This means that you can be hypothermic in the morning and experience heat exhaustion in the afternoon of the same day. Short afternoon storms are common and these often drop the temperature by 30 degrees. When combined with some wind and some sweaty clothes, that can be deadly if you don’t react properly.
One strange phenomenon is that it often will be pouring rain at 60 or 70% humidity. With the cold air, it can dump water without being saturated. Since the air isn't saturated, evaporation occurs much faster, pulling heat out of the air...any your body.
In the humid areas, rain water can be like taking a warm shower. In the arid west, rain water tends to be MUCH colder. As it evaporates, it pulls the heat out of your body and causes hypothermia very quickly.
