Earth’s Changing Atmosphere Chapter 15

Earth’s atmosphere supports life Atmosphere – a layer of air and gases that surrounds and protects the earth Keeps Earth warm Transports energy to different regions Although important, it is very thin comparatively

Atmosphere characteristics As you go up in the atmosphere (altitude), the air becomes less dense or thinner. Density is the amount of “stuff” in a certain amount of space ( volume) The higher you get the less air molecules are between you and the top of the atmosphere. That means there are less air molecules pushing on you ( less air pressure)

A recipe for the atmosphere? Mostly gases Some tiny solid or liquid particles 78% nitrogen 21 % oxygen 1% trace gases ( argon, carbon dioxide, etc)

Sudden changes in our atmosphere Volcanic eruptions -lots of gases and ash into the atmosphere in a short period of time. Forest fires - carbon dioxide, smoke and ash enter the atmosphere Dust storms - clouds of eroded soil particles enter the atmosphere by strong winds.

Energy movement in the atmosphere Radiation- energy transfer through waves Conduction - energy transfer by direct contact Convection –energy transfer by movement of liquid or gas (hot/less dense material rises as cooler/more dense material sinks)

Layers of the atmosphere Troposphere ( closest to the earth) Stratosphere ( contains the ozone layer) Mesosphere Thermosphere

Gases in the atmosphere absorb radiation Certain gases in the atmosphere help protect Earth from ultraviolet and infrared radiation The Ozone layer is a layer of ozone in the stratosphere that absorbs harmful ultraviolet radiation

What keeps the Earth Warm? A “blanket” of greenhouse gases allows the suns radiation to pass through but then traps some of the reflected heat in. This process is called the greenhouse effect.