The Atmosphere

What is the atmosphere? The atmosphere is a mixture of gases that surround the earth. It holds the oxygen you breathe and protects you from the sun’s radiation. It also helps keep us warm.

How does it work?

Composition 78% nitrogen (N) 21% oxygen (O) 1% small particles of dust, ash, sea salt, dirt, and smoke

Water Water can be found in the atmosphere as: Liquid Solid Gas

Air Pressure Air pressure is the measure of the force that air molecules push against a surface. Air pressure is strongest at the surface because there is more air above you. As altitude increases, air pressure decreases. This is because air is less dense the higher up you go.

Atmosphere and Temperature Air temperature changes with altitude. Temperature differences mainly result from the way solar energy is absorbed. Some gases absorb energy better than others.

Altitude, Temperature, and Pressure

Layers of the Atmosphere Thermosphere Mesosphere Stratosphere Troposphere

Names and Their Meaning Sphere = Ball Tropo = turning or change Gasses turn and mix Strato = layer Gasses are layered Meso = middle Middle layer Thermo = heat Temperature is highest

Troposphere: Where We Live Densest layer – makes up 90% of the atmosphere’s mass Contains almost all carbon dioxide, water vapor, weather, and life Temps vary greatly

Stratosphere: Home of the Ozone Temperature rises as altitude rises in this layer because ozone absorbs heat from radiation. Ozone protects the troposphere from harmful ultraviolet radiation.

Mesosphere: Middle Layer Middle and coldest layer Temp decreases as altitude increases

Thermosphere: The Edge Temp increases with altitude Heat is a transfer of thermal energy, but the atoms are so far apart in the thermosphere that no heat is transferred. Although the temperature may be high, it is not hot.

Ionosphere The Ionosphere is in the upper mesosphere, lower thermosphere. Particles get heated by radiation and become electrically charged. Charged particles are called ions. These particles sometimes radiate energy in the form of light called auroras.

Exosphere Just past the thermosphere is the exosphere. Very few molecules. The outer most layer.

Review Why does temperature vary from one layer to another? Why does air pressure decrease as altitude increases? Why does the thermosphere have high temperatures but does not feel hot? What two gasses make up most of the atmosphere? What are the layers of the atmosphere, in order from bottom to top?