On June 20th, the sun is directly overhead the Tropic of Cancer (~23.26 degrees N). So if you are standing on this line, the sun is directly overhead. As you move north, the angle of the sun continues to decrease.
I would say there are 2 factors to what you observe. The main culprit is lack of water vapor in the air (this is dependent on location, particularly elevation and being away from the ocean). I always refer to Miami, FL and Phoenix, AZ. Miami gets more sunlight, but it rarely ever reaches 100F. The reason is much of the sun's energy goes into the water cycle, particularly phase transformation (liquid to gas) and convection.
Humidity levels are so low out west, so the sun's energy goes into warming the air. Elevation/location is vital to reaching 100F in the summer. Temperature is proportional to the thickness of the atmosphere. Death Valley, CA, is below sea-level and is really hot. Same thing with the middle east. Higher elevations have much thinner air, so infrared energy isn't as readily absorbed as down near sea-level.
As a corollary to elevation, the second culprit is the like a chinook. Chinook is 'snow-eater', a phenomena often seen in southern Alberta in winter. It's down-slope winds, and the idea is that adiabatic warming occurs with the right direction and velocity of winds. I know California gets the Santa Ana winds. It's all a similar process.
So, lack of moisture and downslope winds would be the 2 reasons. Too many words? LOL! |
