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