Energy and Heat Transfer in the Atmosphere

Waves Earth receives electromagnetic energy from the sun in 3 different forms: visible light: allows us to see -- ROYGBV red and orange light have the longest wavelengths (distance between two waves) blue and violet have shorter wavelengths but higher frequency (# of waves repeating in a given space) infrared radiation felt as heat but can’t be seen longer wavelengths and ____ frequency than red light ultraviolet radiation shorter wavelength than violet light, _____ frequency Can cause sunburns, skin cancer and eye damage

Seeing Colors Colors we see are reflecting that wavelength of visible light and absorbing all other colors. A red car appears red because it reflects red wavelengths of light and absorbs OYGBV The gases in our atmosphere ________ blue light waves more than any other color, so the sky appears blue during the day. During sunrise/sunset, sunlight passes through a greater thickness of atmosphere and reflects longer wavelengths of light (red and orange) causing the sun and sky to look red.

Energy in the Atmosphere As sunlight travels through our atmosphere, some of its heat (infrared radiation) is absorbed and some is reflected: 50% absorbed by Earth’s surface (land/water) 25% reflected back into space by atmosphere 20% absorbed by greenhouse gases in atmosphere Gases like water vapor, CO2, and CH4 (methane) absorb and radiate some of the sun’s heat Too much greenhouse gas = too much heat 5% reflected by Earth’s surface back into atmosphere

Heat Transfer Heat refers to the energy transferred from a hot object to a cool object. On Earth, the sun’s heat is transferred in 3 different ways: 1. Radiation: direct transfer of energy through empty space, and it can be felt as heat.

Conduction 2. Conduction: The transfer of heat from one substance to another substance that it is directly touching. Occurs solid  solid or solid  liquid Where is conduction occurring in this picture?

Convection 3. Convection: The transfer of heat by the movement of fluids (gas or liquid). Moleculues are free to move from place to place and take their heat with them.

Heat Transfer in the Atmosphere The sun transfers heat to the Earth’s surface through radiation. Through conduction, heat is transferred from the surface to the air above it. As air is heated, molecules collide with each other and spread apart, making the air less dense. Less dense air rises, and cooler, denser air sinks (hot air rises and cold air sinks). The upward movement of warm air and the downward movement of cool air form convection currents. These currents move heat throughout the troposphere.