In this unit, we will be discussing Latitude as a climatic control. By latitude we are not talking about geographic location. Rather our interest will center on the effect of latitudinal location on the receipt of solar energy at the Earth's surface. To a degree the Greeks were on to the idea when they proposed their Torrid, Temperate and Frigid temperature zones over 2000 years ago.
02. Specifically in this section on Latitude, we are going to cover four topics:
Earth-Sun Relationships. This section will deal with the actual receipt of solar energy at the Earth's surface. The receipt of solar energy is directly related to the relationships which exist between the Earth and the Sun across the year. All of you would recognize the basic relationships. Each day we can see that the Sun "rises" in the east and sets in the west. Most would also recognize that over a 12 month period the Sun "moves" from north to south in our sky. In other words, the Sun not only "moves" from east to west, but also north to south. And how about the fact that days tend to get longer in the northern hemisphere from December 21 to June 21, and then grow shorter from June 21 to December 21? Earth-Sun relationships cause changes in the amount of insolation received day to day and seasonally. And, depending upon the relationship, the amount of insolation changes locationally and through time. The resultant temperatures created due to these changing relationships create pressure differences which are largely responsible for winds. The winds in turn drive the ocean currents and our weather.
The transform plate boundary between the Pacific and North American Plates in western California formed fairly recently. About 200 million years ago, a large tectonic plate (called the Farallon Plate) started to subduct beneath the western edge of North America.
