1. Weather An Overview

2. Atmosphere b Is a mixture of the gasses that surround the Earth.  The atmosphere gives us the air we breath as well as protects us from some of the sun ’ s harmful rays. b The atmosphere is also the location where a lot of the weather phenomena that we will be learning about happens.

3. Air Pressure b Is the measure of the force with which air molecules press on the surface. b When your ears pop the pressure inside your ears and outside your ears become =

4. Altitude b Is defined as the height of an object above the surface of the Earth. b As altitude increases air pressure decreases b Why is this?

5. Layers of the atmosphere  Based on temperature the Earth ’ s atmosphere is divided into 4 layers b 1) Troposphere b 2) Stratosphere b 3) Mesosphere b 4) Thermosphere

6. Troposphere b Lowest layer of the atmosphere b Densest atmospheric layer  Earth ’ s water vapor, air pollution, clouds, weather, and life forms are found at this layer

7. Stratosphere b The air is very thin and contains very little moisture b Temp approx. -60 C degrees b In this layer the temperature rises with altitude because of ozone which is a gas that heats up the atmosphere

8. Mesosphere b Coldest layer: can be as low as -93 degrees C b Large wind storms can take place with wind speeds reaching more than 150 mph

9. Thermosphere b The upper most atmospheric layer in which the temperature can reach 1700 degrees C. b Very few molecules at this layer b Picture to right shows heat at this layer

10. Heating of the Atmosphere b Heating of the atmosphere takes places in 3 ways b 1) Conduction b 2) Convection b 3) Radiation

11. Radiation b This is a method of heat transfer in which heat travels through empty space b The best example of this is the suns rays heating up the Earth. The heat will travel through outer space (empty) reach our planet and heat up the surface

12. Conduction b Is the transfer of thermal energy from one material to another by direct contact b Example would be walking on the sidewalk and heating up your foot from the heat that has built up on the ground

13. Convection b Transfer of thermal energy by circulation or movement of a liquid or a gas b For example: air is heated and it rises then it cools and it sinks. This circular up and down motion pushes atmospheric gases on our planet.

14. “ The Green House Effect ” b This is the process in which gases in the atmosphere trap thermal energy. Keeps the surface of the Earth much warmer  Global warming: This is when the Earth’s average temperature increases each year. Average temperature is the average of all the locations on earth during 1 whole year.

15. Wind b Is very simply defined as moving air. b It is created from differences in air pressure caused by temperature differences. b Usually there is greater pressure at the poles and less at the equator. There fore wind usually moves from the poles toward the equator.

16. Coriolis Effect  The curving of moving objects, such as wind, by the earth ’ s rotation is called the “ coriolis effect ”. b Cont. on page 404 b Read 402 - 407 b Page 407 questions 1-4

17. Types of Winds b Trade Winds: winds that blow from 30 degrees latitude to the equator b Westerlies: wind belts found in both the northern hemisphere and southern hemisphere between 30 - 60 degrees latitude b Polar Easterlies: wind belts from the poles to 60 degrees latitude

18. The Jet stream b The jet stream is very high speed band of air that blows in the troposphere and lower stratosphere b The jet stream can reach wind speeds of up to 250 km / hr b This stream of air switches direction often, and in doing so steers storms / fronts across our country

19. Jet Stream

20. Pollution b Primary pollutants: put in the air by human or natural activity b Secondary Pollutants: This type of pollutant reacts when two primary pollutants react to form a new secondary pollutant

21. Acid Precipitation b When fuels get burned some of the remnants go up into the air where it mixes with water vapor and then comes down as acid rain. This rain can weather metal, wood (ect.) at and advanced rate. b Ex. Statue of liberty, Bridges

22. Assignment b In the past few decades Pollution has become a major problem for our country. Please write an essay stating what you would do if you had an unlimited budget and where in charge of environmental policies in our country. How would you go about fixing this major problem?

23. Water Cycle b This relates to the continuous movement of water from lakes / rivers to clouds to the ground and back up again b Vocabulary: condensation / vaporization

24. Humidity b Is defined as the amount of water vapor or moisture in the air. b relative humidity: Is the amount of moisture in the air compared to the maximum amount of humidity it can hold at a certain temperature

25. Dew Point b Is defined as the temperature air must cool to be completely saturated.

26. Clouds b A cloud is a collection of millions of tiny little water droplets or ice crystals which are suspended in the air b In this next section we are going to learn about the different types of clouds

27. Cumulus Clouds b Puffy white cloud that tend to have a white bottom ( cotton balls) b These clouds form when warm air rises b They usually represent good weather, unless they get very large they can represent thunderstorms

28. Stratus clouds b This type of cloud forms in layers b This type of clouds covers large areas of the sky usually blocking out the sun b Caused by a gentle lifting of a large body of air into the atmosphere b NIMBOSTRATUS: clouds that are stratus in origin however dark in color. They usually produce light to heavy rain

29. Cirrus Clouds b Thin feathery white clouds formed at high altitudes b These types of clouds form when the wind is strong b They may represent bad weather If they begin to thicken and lower in altitude

30. Precipitation b Is water in liquid or solid form that forms from the sky to the surface of the Earth b There are four major types of precipitation b Rain, Sleet, Snow, Hail  In order for a cloud droplet to form as precipitation it must increase it ’ s size 100 times

31. Snow / Sleet b Snow forms when water vapor is so cold that it falls in solid form as snow b Sleet forms when rain falls through a layer of freezing air b If the rain does not freeze till it hits the surface then it forms something called glaze or (ground ice)

32. Hail b Solid precipitation that forms as balls or lumps of ice b Usually forms when gust of air carries rain droplets to a high,, cold altitude where it freezes and then falls to the Earth as a ball of ice called hail