Heating the Atmosphere Radiation Conduction The Earth receives its energy from the sun through radiation The transfer of energy as electromagnetic waves. –Energy absorbed by a surface heats –Example: Your skin feels the sun as it absorbs the energy & warms The transfer of thermal energy from one material to another by direct contact –Always moves from the hotter to the colder –Example: your feet touching hot sand

Convection Greenhouse Effect The transfer of thermal energy by the circulation or movement of a liquid or gas –Heated = less dense, rises –Cools = more dense, sinks –Called convection current –Example: heating your home, boiling rice The Earth’s heating process, in which the gases in the atmosphere trap thermal energy. –CO 2, water vapor keep energy from leaving atmosphere –Similar to a blanket keeping you warm

Radiation Balance Is it really a problem? The balance between incoming and outgoing energy –If CO 2 & other greenhouse gases increase, the balance could be affected –Temperatures rise, changing plant & animal environments Some scientists believe there is a natural warming & cooling process for the Earth. –They feel this current warming trend is not a problem –Studies show that while there is a natural warming & cooling for the earth, the current one is greater than ever before –Many nations (not the US), have signed the Kyoto Agreement to help reduce Greenhouse gases

Kyoto Agreement Countries