Weather Factors Chapter 16

Energy in Earth’s Atmosphere Heat is a major factor in the weather Movement of heat in the atmosphere causes the temperatures to change, winds to blow, and rain to fall

Energy from the Sun Nearly all the energy in Earth’s atmosphere comes from the SUN. The energy travels to Earth as ELECTROMAGNETIC WAVES, which is a form of energy that can move through the vacuum of space. E- waves are classified as WAVELENGTHS, which is the distance between waves. RADIATION is the direct transfer of energy by e-waves. Most energy from the sun travels to Earth in the form of VISIBLE light and INFRARED radiation. Small amounts arrive as ULTRAVIOLET radiation. NEED TO KNOW: ** Electromagnetic waves (e-waves) are energy ** Radiation is the direct transfer of e-waves (energy) ** It travels in the form of visible light, infrared radiation, and small amounts of UV radiation.

Visible Light Nonvisible radiation LONGER WAVELENGTHS SHORTER WAVELENGTHS Visible Light All colors you see in the rainbow Different colors are the result of different WAVELENGTHS What color is the longest wavelength? What color is the shortest wavelength? Infrared radiation Wavelengths are LONGER than red light Not VISIBLE, FELT as heat UV (ultraviolet) radiation Wavelengths SHORTER than violet light Causes sunburn, skin cancer, eye damage Nonvisible radiation

Energy in the Atmosphere Sunlight must pass through the ATMOSPHERE before reaching Earth’s surface Some sunlight is absorbed or reflected by the atmosphere BEFORE it reaches the surface The rest passes through the atmosphere to the surface What percent is reflected? What percent is absorbed by Earth’s surface? 25% 5% 20% 50%

ENERGY ABSORBED ENERGY REFLECTED Ozone layer in the STRATOSPHERE absorbs most UV RADIATION Water vapor and carbon dioxide absorb some INFRARED RADIATION Clouds, dust, and other gases absorb ENERGY Some sunlight is reflected. CLOUDS are like mirrors and reflect back into space. Dust particles and gases reflect light in all directions called SCATTERING

WHY IS THE SKY BLUE? When you look at the sky, the light you see has been SCATTERED around by gas molecules in the atmosphere. Gas molecules scatter the short blue wavelengths of visible light more frequently than longer wavelengths. Scattered light therefore looks BLUER than ordinary sunlight… sky = blue  Sunrise or sunset looks different because it passes through a greater thickness of atmosphere. The scattering removes more blue light and causes the sun to look RED. BONUS QUESTION: Why isn’t the sky blue in space?

Energy at Earth’s Surface Greenhouse effect is the process by which gases hold heat in the air.

Checkpoint The three types of radiation that Earth receives from the sun include ____________ ___________, _______________ ________________, and _________________ _______________. We can detect visible light because we can _________ it. We can detect infrared radiation because we can _________ it. Which form of radiation from the sun has the longest wavelength? ____________________ Which has the shortest? ___________________ Which color of visible light has the longest wavelength? Most of the sunlight that reaches Earth is _____________ by the atmosphere or by Earth’s surface. (absorbed/reflected) The sky is blue because those wavelengths are ______________ in the atmosphere. The energy from the sun that is absorbed by Earth’s surface ____________ the land and water. Most of it is then radiated back into the atmosphere as _____________ _____________. The process by which gases hold heat in the air is called the _____________________ _________________.