Front Range Mountain Wave Rain Shadow

When the winds aloft are from the West and a lot of moisture is in the air, you get something looking like this picture. Not every day, and not for miles and miles, thankfully. Think of a wave breaking over a reef. The break here returns to ground about 40 miles East of the Colorado Front Range. The area from the base of the Front Range to where the wind returns to the Plains is called the "rain shadow". From the air you can see the ground going from green to brown.

Flying through this will give you a five to ten minute break from the tedium of your cross country flight.

Seasoned airline passengers in and out of Denver have a good reason to depart/arrive either very early in the morning or late at night.