GEOG 1001 Lecture Notes - Lecture 4: Thermosphere, Subsolar Point
Document Summary
June 21st is the summer solstice: sun is directly overhead at 23. 5 degrees n (tropic of cancer). Solar declination/ subsolar point : when the sun is directly overhead. Between 23. 5 degrees north and 23. 5 degrees south, the sun will be directly overhead twice. At exactly 23. 5 degrees north and south, the sun will be directly overhead once. December 21st is the winter solstice : sun is directly overhead at 23. 5 degrees s (tropic of capricorn). On the equinoxes, the earth experiences equal day and night (12 hours of day and 12 hours of night). Atmosphere extends 32,000 km from the surface. Thermosphere is at 480 km through the top of the principle atmosphere. The atmosphere is denser at the earth"s surface. Dry air is about 78% nitrogen, 21% oxygen, and a mix of carbon, argon, and other gasses. The air also contains water vapor, which absorbs heat. Air temperature drops, on average, about 6. 4 degrees c per 1000 m.
