Chapter 1 – Earth’s Changing Atmosphere Section 1.3 – Gases in the atmosphere absorb radiation
Objectives • BEFORE, you learned • Solar radiation heats Earth’s surface and atmosphere • Earth’s surface and atmosphere give off radiation • The ozone layer is in the stratosphere
• NOW, you will learn • More about how radiation and gases affect each other • About the ozone layer and ultraviolet radiation • About the greenhouse effect
I. Gases can absorb and give off radiation • The atmosphere can affect light in four ways
– It can absorb light – It can reflect light – It can let light pass through – It can emit (give off) light
• There are forms of radiation humans cannot see
– Visible light – light that we are able to see with our naked eye, made up of the 7 colors ROY G BIV = white light – Ultraviolet radiation – waves that have more energy than visible light (higher frequency) – Ultraviolet radiation can cause sunburn, skin cancer, damage to your eyesight, paint, plastic, harm crops, etc – Infrared radiation – waves that have less energy than visible light (lower frequency) – Infrared radiation usually warms the materials that absorb it – Electromagnetic Spectrum – everything from what we can to what we cannot see. It includes UV rays, X-rays, Microwaves, Gamma rays, TV/radio waves and visible light
II. The ozone layer protects life from harmful radiation
• Ozone – is made up of 3 atoms of the oxygen element
• The ozone protects life by absorbing harmful UV rays from the sun • The ozone layer is located in the second layer (stratosphere)
III. The greenhouse effect keeps Earth warm. • The Greenhouse effect is gases that absorb and • • •
emit infrared radiation, which keeps energy in Earth’s system for a while Greenhouse gases give off infrared radiation Examples of greenhouse gases: carbon dioxide, methane, water vapor, nitrous oxide, and other gases that absorb and give off infrared radiation If the atmosphere had no greenhouse gases, Earth temperature would only be -18 degrees C/ 0 degrees F
• Atmosphere without
• Atmosphere with
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Greenhouse Gases - infrared radiation would go straight through to outer space - water freezes and too cold for most forms of life on Earth to survive
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Greenhouse Gases infrared radiation is kept within our atmosphere - water stays in liquid form