Since the equator is tilted 23. 5 with respect to the path the follows in its orbit around the sun, therefore: at higher latitude, light strikes at a lower angle, and is spread over a greater area. At the equator, the sun shines almost perpendicular on earth"s surface. (figure 4. 1) In northern hemisphere, seasonal variation in temperature increases significantly (less ocean to moderate temperature change. Warming air cools down as it rises, as it cools down its ability to hold water vapor decreases heavy rain. As the cool air continues to expand and replaced from below by surface-level air moving in. this type of circulation pattern is called hadley circulation. Jet stream: a rapidly moving west-to-east air current that forms at the high altitude junction of 2 atmospheric circulation cells (hadley and ferrel cells). Coupled cells + coriolis effect = prevailing wind patterns.