13.4 - The Atmosphere

Characteristics of the Atmosphere It is a blanket of moisture-filled air that surrounds the earth It consists 78% nitrogen, 21% oxygen, 1% other gases (argon, carbon dioxide and water) It has ozone in its upper layers which absorb harmful UV rays from the sun It protects us from meteors (they vaporize due to the friction with the atmosphere) SEE ALBERTA CLIP It keeps the earth warm enough for us to live BRRRRRR!! DO YOU KNOW HOW COLD SPACE IS???

Layers of THE Atmosphere

Temperature Gradient Temperature Gradient: A change in temperature over a vertical distance In the troposphere, the temperature gradient is -0.65° per 100 m in altitude Q: What is the temperature at the top of an 8000 m mountain if the temperature is 18°C at the foot of the mountain? A. -34°C !!!

Layers Again….

Layers in Order…(FROM EARTH TO SPACE) 1. Troposphere – up approx 12 km Closest to the Earth’s surface Where all weather takes place Air is in constant motion with both vertical and horizontal currents Pressure decreases as altitude increases Has very small amounts of ozone 2. Tropopause Contains more ozone than troposphere Is warmer than the troposphere because it absorbs UV rays from the sun

3.STRATOSPHERE 12-50 km above the Earth’s surface Higher levels of ozone than any other layer 4.MESOSPHERE Temperatures are very low here 50 to 80 km above the earth Very low density Meteors from space usually burn up in this layer due to air friction

5.Thermosphere (Ionosphere) 80 km to 500 km from Earth’s surface Fewest air molecules Also called ionosphere b/c the Sun’s radiation causes particles to become electrically charged ions The Northern and Southern lights (aurora borealis) are produced by these ions These charged particles also reflect radio signals so they can travel around the World

6. Exosphere Outer limits! SPACE The thin, outermost layer Very few particles (hydrogen) spread out very far - DISCOVERY COMMERCIAL

Atmospheric Layers: Scale Diagram Activity  You will be producing a diagram of the atmospheric layers. These layers will be proportional in thickness to each other.   Troposphere 0 – 12 km Tropopause 12 – 16 km Stratosphere 16 – 50 km Mesosphere 50 – 80 km Thermosphere 80 – 500 km Exosphere 500 - ??? Km

 Your scale will be 1 cm = 10 km Obtain 4 or 5 strips of paper from the teacher. Start by representing the surface of the Earth and then proceed upwards through the layers. Use the thickness of the layers and the given scale to draw your diagram. Clearly label all distances (in km) and label all atmospheric layers in their proper location. Represent important information about each layer. Use color. Be neat and tidy.