ANT200Y1 Midterm: 101 MT key Q 3-2.docx
Document Summary
It penetrates the earth"s atmosphere fairly easily, but about 30% of it is returned to space reflected from clouds and aerosols and from the surface (earth albedo). It plays no role in heating the earth. About 50% gets through the atmosphere to the surface where it is absorbed then reradiated. It"s the reradiated energy that heats the earth. Because the earth is a cool emitter the reradiated energy is longwave. This is not easily lost back to space because it is selectively absorbed by greenhouse gasses and reemitted both upwards and downwards. The other fluxes in the atmosphere involve mostly changes in the state of water (latent energy exchanges): global food production. We feed the world primarily with four cereals wheat, barley, rice and corn/maize. The main reason is the adaptability of these crops to a huge range of climates and substrates. This adaptability is a product of their genetic flexibility and their pre- adaptation to open, disturbed environments.
