How the Earths Spin Affects Weather

How does the Earth’s spin affect weather? If the earth did not spin, have a tilt on the axis and have water, the air would heat up from the sun and rise causing it to move towards the poles where it would be cooled and return to the equator. A very simple weather pattern would occur of high pressure at the poles and low pressure at the equator.

Due to the rotation, axis and water the Earth has three circulation cells, Hadley, Ferrel and Polar. The Hadley Cell is low latitude air movement towards the equator that with heating rises and moves toward the poles in the upper atmosphere. This is where the tropical and sub-tropical climates reside. The Ferrel Cell is the area mid way between the equator and the Polar Cell where air flows toward the poles and in an east direction near the surface and towards the equator and west in the upper atmosphere. The Polar Cell is where the air rises and travels towards the poles and then sinks and forms high pressures. At the surface the air moves outward from the pole and easterly. According to the National Weather Service web site at the thirty degree N/S Latitude there is a high pressure band and at the 50 degrees to 60 degrees N/S Latitude there are low pressure bands.

The earth’s rotation is also responsible for creating the jet streams; the movement of air is not directly north or south because of the location on or above the Earth and is constantly going in an easterly direction. Air moves faster in an easterly direction as it gets farther from the equator. Jet streams can be four to eight miles in height from the surface and move very fast at speeds higher than 275 mph. It is interesting to note that jet streams follow the sun, meaning in the northern hemisphere in the summer the jet streams move northward towards the pole and when fall comes they move southward towards the equator.

All of these variables created by the earth’s rotation, the tilted axis, and jet streams effect weather and create climates. The Earth has many climates. Climate is the term used to describe the average weather of region. Weather changes daily but climate is what can be expected on average in certain geographical areas. The tropical climate is where the average temperature is 64 degrees or above and rain fall averages about 59 inches per year. The dry climate is where the deserts happen, these areas are often surrounded by mountains and there is more potential for evaporation and transpiration then precipitation. Basically water will evaporate faster and off of plants more than it will rain. The moist subtropical mid-latitude climates have warm humid summers and mild winters, like the south east sections of the United States. While the moist continental mid-latitude climate is where there are warm to cool summers and cold winters. The warmest months see temperatures above 50 degrees and the coldest can be lower than -22 degrees. These areas would be effected in winter by sever snowstorms, strong winds and bitter cold much like the areas of the very northern parts of New England in the United States. Polar climates like Alaska, Greenland and Antarctica have cold temperatures all year round and usually the temperature never goes above 50 degrees.