1. EARTH’S ATMOSPHERE

2. Origins of the Atmosphere Boom. Our atmosphere was created by gases that vented from erupting volcanoes. Outgassing There were three main gasses emitted: 1.Water Vapor 2.Carbon dioxide 3.Nitrogen

3. Now the atmosphere is mainly…. If your not sure look at your….. ESRT 1.Nitrogen 2.Oxygen How did this occur? Plant life began to grow so they converted carbon dioxide to oxygen Photosynthesis

5. The Structure of the Atmopshere The atmosphere is broken into four layers: 1.Troposphere 2.Stratosphere 3.Mesosphere 4.Thermosphere The layers in between the spheres are called: -pauses

7. Changes in Air Temperature There are two cycles that control our weather: 1.The daily weather cycle 2.The season weather cycle

8. Daily Weather Cycle Morning----------- 2pm---------------- 6pm----------------

9. Seasonal Cycle MARCH 21-23DECEMBER 21-23JUNE 21-23SEPTEMBER 21-23

11. What Causes Air Pressure? Air Pressure: is the weight of the atmosphere Proof: Weigh a flat basketball compared to a basketball filled with air. At sea-level, the air pressure is nearly 15 lbs per square inch, or 1013.2 mb. Millibars: the metric unit of atmospheric pressure.

12. STRAW PROOF AIR GOES OUT OF THE STRAW SO PRESSURE DECREASES Less pressure means that the liquid has nothing holding it back so it moves up the straw

13. Measuring Air Pressure ometer: Instrument that measures air pressure. Use to use mercury as a liquid in it to gauge the air pressure (like a thermometer) so that is how we got the unit inches of mercury. In. of Hg We also use millibars to measure air pressure Bar

15. Factors that Affect Atmospheric Pressure Altitude As air rises it expands and there is less gravity pushing down on it. More elevation = less air pressure Indirect relationship Altitude (elevation) Air Pressure

16. Factors (cont) Temperature: If air is cooled it comes together and becomes more dense More dense air makes it heavier so there is more air pressure If air is heated it’s molecules expand and it becomes less dense Less dense air makes it lighter so there is less air pressure Air Pressure Temperature

17. Factors (cont) Humidity Is the amount of water vapor in the air Humid air is less dense than dry air The mass of water is less than the mass of nitrogen The atmosphere is made up of primarily which gas…. Nitrogen More humidity = less air pressure Air Pressure Humidity

18. Dew Point When the humidity of the air cools to a certain point, you see water in some form. This temperature in which we see water is what we call the dew point. The dew point comes mostly when the greatest change in temperature occurs which is….. (Think the daily weather cycle) The morning

19. How to Find the Dew Point Using a sling psychrometer you: 1.Record the dry bulb reading 2.Record the difference between the dry bulb and the wet bulb (wet bulb will always be less) 3.Go to your ESRT and match up those two numbers to find the Dew Point

20. Dry Bulb: 22 °C Wet Bulb: 20 °C Diff: 2°C

21. Relative Humidity The percentage of humidity in the air is called the relative humidity. We use a sling psychrometer to find this as well. You also use the same procedure to find the relative humidity.