2Guide for ReadingIn what form does energy from the sun travel to Earth?What happens to energy from the sun when it reaches Earth?Which color of visible light has the longest wavelength?Why would particles from volcanic eruptions make sunsets and sunrises more red?
3Energy from the Sun Energy travels to Earth as electromagnetic waves Form of energy that can travel through spaceClassified according to wavelengthThe direct transfer of energy by electromagnetic waves is called radiation
4Energy from the SunMost of the energy from the sun reaches Earth in the form of visible light and infrared radiation, and a small amount of ultraviolet light.
6Energy from the SunInfrared radiation is a form of energy with wavelengths that are longer than red light.Not visibleCan be felt as heatExample: lamps used to keep food warm in restaurants give off both visible red light and invisible infrared light
7Energy from the SunThe sun also gives off ultraviolet radiation, which has wavelengths that are shorter than violet light.Cause sunburnsCan cause skin cancer and eye damage
8Energy in the Atmosphere When the rays of the sun pass through the atmosphere, some of the energy from the sun is absorbed within the atmosphereSome infrared radiation is absorbed by water vapor and carbon dioxideThe ozone layer in the atmosphere absorbs most of the ultraviolet radiationClouds, dust and other gases also absorb energy from the sun
9Energy in the Atmosphere Some sun rays are reflectClouds act like mirrors, reflecting some solar energy back into spaceDust particles and molecules of gases in the atmosphere reflect light from the sun in all directions
10Energy in the Atmosphere Reflecting of light in all directions is called scatteringWhen you look in the sky, the light you see has been scattered by gas molecules in the atmosphereGas molecules scatter short wavelengths of visible light more than longer wavelengthsWhy the sky is blue!
11Energy in the Atmosphere When the sun is rising and settingLight form the sun passes through a thicker part of the atmosphereMore light from the blue end of the spectrum is removed by scatteringThe remaining light from the sun contains mostly red and orange light
12Energy at Earth’s Surface Some of the sun’s energy reaches Earth’s surface and is reflected back into the atmosphereSome is absorbed by the land and water and changed into heat
13Energy at Earth’s Surface When Earth’s surface is heated, it radiates some of the energy back into the atmosphere as infrared radiation.The IR cannot travel all the way through the atmosphere back to spaceAbsorbed by water vapor, carbon dioxide, methane, and other gases
14Energy at Earth’s Surface Absorbed radiation heats the gases in the air and a “blanket” around earth is formedHolds heat in the atmosphereThe process by which gases hole heat in the air is called the greenhouse effect.Keeps Earth’s temperature comfortable for most living things