The Atmosphere

What is the atmosphere? The envelope of gases that surrounds Earth

Importance of Atmosphere Weather happens here. (Weather is the condition of the atmosphere at a certain place and time.) Our atmosphere makes life possible on our planet. Provides us with oxygen. Keeps surface warm so water can exist as a liquid. Protects the surface from dangerous radiation from the sun.

Composition of the Atmosphere (air) Nitrogen makes up 80% of our atmosphere Oxygen makes up 21% Argon makes up almost 1% All other gases have only trace amounts

Atmospheric or air Pressure The atmosphere or air exerts pressure on the Earth that decreases with increasing altitude This is due to the fact that with increasing altitude, there is a decrease in the column of gases above the Earth’s surface

At greater altitudes, the same volume contains fewer molecules of the gases that make up the air. This means that the density of air decreases with increasing altitude.

Why the air pressure is greatest at the Earth’s surface? What is the instrument that is used to measure air pressure? Barometer Why the air pressure is greatest at the Earth’s surface? Gravity pulls gas molecules toward the earth’s surface.

Layers of Atmosphere

video http://studyjams.scholastic.com/studyjams/jams/science/weather-and-climate/earths-atmosphere.htm

Why is the atmosphere divided into four layers? Temperature variations in the four layers are due to the way solar energy is absorbed as it moves downward through the atmosphere.

Troposphere Troposphere – “ Tropo” means changing or turning As altitude increases, temperature decreases. As altitude increases, density decreases. -60 degrees Celsius at the boundary of Troposphere.

Stratosphere “Strato” means layer or spread out Has ozone ( three atom oxygen ) layer – protects the earth from harmful UV radiation coming from the sun As altitude increases the temperature increases Layer of the atmosphere where gases do not mix

Mesosphere “Meso” means middle Meteor showers happens in this layer As altitude increases the temperature decreases to – 90 degrees Celsius

Thermosphere “Thermo” means heat Outermost layer which blends with outer space Very hot temperatures (1800 degrees Celsius )

Two sublayers of Thermosphere Lower sublayer – Ionosphere Auroras happens here Upper sublayer – Exosphere Satellites are stationed here.

The structure of the atmosphere based on temperature differences.

Rap http://www.watchknowlearn.org/Video.aspx?VideoID=26842 http://earthguide.ucsd.edu/earthguide/diagrams/atmosphere/