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
• 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
I. Gases can absorb and give off radiation
• 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 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
• Atmosphere with Greenhouse Gases
• infrared radiation is kept within our atmosphere
• - water stays in liquid form
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