Presentation on theme: "Chapter 17: The Atmosphere"— Presentation transcript:
1 Chapter 17: The Atmosphere Weather - the state of the atmosphere at any given time and place.Weather is constantly changing.Climate - is weather over a long period of time, describes regions.
2 Measure Of Weather 1. Temperature 2. Humidity 3. Precipitation Type 4. Precipitation Amount5. Air Pressure6. Wind Speed7. Wind Direction
3 Atmosphere Composition Different today than long time ago!How?2 main gases make up 99%Nitrogen - 78% & Oxygen - 21%Carbon Dioxide - small amount/importantWater (vapor)- amount variesBoth absorb heat given off by Earth
5 Dust particles are important - allow water droplets to form around them so we can have precipitation.Ozone : O3 - found in stratosphere- protects us from UV radiation- we harm ozone by using CFC’s… aerosols, AC, fridges, etc.- Ozone hole in ‘85
6 Height & StructureThe atmosphere rapidly thins as you go away from Earth.Pressure reduces as you go up.At sea level air pressure is about 14.7 lbs per square inch.Generally speaking temperatures cool as you go up!
7 4 atmospheric layers:Thermosphere - top layer,auroras, boundary to space, very thin amount of gases, temps. Increase as you go upMesosphere - next layer down, meteors hopefully “burn up” here, coldest layer, temperatures get colder as you go up.
8 Stratosphere - contains ozone layer, temperatures increase as you go up. Troposphere - closest layer to Earth, contains all weather, temperatures decrease as you go up.
10 Earth-Sun relationships Solar energy is not evenly distributed.(latitude, time of day, & season)Earth has 2 principle motions:1.Rotation - spinning, causes night & day,24 hours (23 hrs & 56 mins.)2.Revolution - orbiting, gives us yeardays
11 Earth’s OrientationSeasonal changes occur because Earth’s position to the sun changes.Earth’s 23.5 degree tilt gives us seasonsNo tilt would mean NO seasons!Read page 481!
13 4 SEASONS: Summer and Winter Solstice means “sun stop” - summer solstice = June 21st=longest day- sun over the Tropic of Cancer- winter solstice = Dec. 21st=shortest day- sun over the Tropic of Capricorn
14 Equinoxes Equinox mean “equal night & day” - spring equinox = March 21st=12 hr sun- autumnal equinox = Sept. 21st=12 hr sun- sun over the equator for both of these
15 17.2 Heating the Atmosphere Heat – energy transferred from one object to anotherTemperature – a measure of how fast the molecules are moving…Hotter moves faster, colder…Heat is transferred 3 waysConductionConvectionRadiation
16 1. Conduction Heat transfer through touching Touching a hot stove Sticking your hands in the snow
17 2. ConvectionHeat transfer from moving particles, like air and/or water.Cold water in the lakeHot water moving around in a pot on the stove
18 3. Radiation Heat transfer by waves Electromagnetic waves (EM) Heat from the sunHeat from a stove burner or fireplaceElectromagnetic waves (EM)These are the waves from the sunThere are types of light we cannot see such as ultraviolet (UV), microwaves, infrared/heat waves (IR), x-rays…
19 What Happens to Solar Radiation? Some is absorbed by the objectSome passes through the objectSome bounces off the objectReflection happens when light bounces off an object
20 From the sun… 50% is absorbed by earth 20% is absorbed by clouds and atmosphere30% is reflected back to space
21 Greenhouse Effect 1. Light from the sun hits Earth 2. Earth warms up and releases heat3. The CO2 and H2O trap the heat like a blanket4. Too much CO2 makes Earth too hot
22 17.3 Temperature ControlsTemperature control – any factor that causes temps to vary from place to place.Latitude – distance from equator…Land or water nearby – land heats up faster and to a higher temperature. Water that’s nearby makes it less extreme.
23 3. Geographic position – where you are makes a difference 4. Altitude – it gets colder as you get higher into the atmosphere.5. Cloud cover – clouds keep it cooler in the day, but warmer at night!* Clouds reflect outgoing heat and/or radiation back to the earth
24 Albedo – how reflective a surface is Albedo – how reflective a surface is. A high albedo reflects a lot of light.Bright materials (snow) have a high albedo, so reflect heat/energy/lightDark colored objects have a low albedo (pavement, grass) so they absorb light/energy/heat.