GEOG 1001 Lecture Notes - Lecture 3: September Equinox, Solar Wind, 40Th Parallel North
Document Summary
The seasons are not caused by changes in sun and earth distances. Aphelion : when the sun and earth are the furthest away. Occurs on july 4th: northern hemisphere is more tilted towards the sun. Perihelion : when the sun and earth are closest. The average sun and earth distance is 150,000,000 km. Plane of the ecliptic : the plane of earth"s orbit. Solar wind : clouds of electrically charged particles. Earth"s magnetosphere deflects the solar wind towards earth"s poles. Sunspots are caused by magnetic storms: sunspots go through an activity cycle every 11 years. Shorter wavelengths have higher energy, and are usually emitted by warmer objects. Long wavelengths have less energy, and are usually emitted by cooler objects. The tropics receive more concentrated insolation due to earth"s curvature. The tropics receive about 2. 5 times more insolation than the poles. Intensity of seasonal change: the sun"s altitude . The sun"s angle above the horizon: solar declination .
