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Chapter15. The Atmosphere. 15-1 Characteristics of the Atmosphere. Atmosphere A mixture of gases that surrounds the Earth Composition Contains gases, solids, and liquids Solids Dust, ash, salt, and smoke Liquid Water. 15-1 Characteristics of the Atmosphere. Atmosphere Composition Gas
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Chapter15 The Atmosphere
15-1 Characteristics of the Atmosphere • Atmosphere • A mixture of gases that surrounds the Earth • Composition • Contains gases, solids, and liquids • Solids • Dust, ash, salt, and smoke • Liquid • Water
15-1 Characteristics of the Atmosphere • Atmosphere • Composition • Gas • Nitrogen • 78% • Released from volcanoes and decaying organisms • Oxygen • 21% • Produced by plants and used by animals • Other 1% • Argon • Carbon Dioxide • Water Vapor
15-1 Characteristics of the Atmosphere • Pressure • Air Pressure • Measure of force with which the air pushes on surfaces • Will decrease with Altitude • The height of an object above the Earth’s surface
15-1 Characteristics of the Atmosphere • Temperature • Changes as you increase altitude • Results from the way solar energy is absorbed • Different layers have different gases that absorb energy
15-1 Characteristics of the Atmosphere • Layers • Troposphere • Lies next to the Earth’s surface • Lowest and densest layer • Contains 90% of the atmosphere’s mass • Contains all the Earth’s carbon dioxide, water vapor, pollution, and life-forms
15-1 Characteristics of the Atmosphere • Layers • Stratosphere • Layer above the troposphere • Air is thin and contains little moisture • Extremely cold at base but temp rises as you go up • Contains OzoneLayer • Absorbs UV radiation • Ozone • Molecule of 3 oxygen atoms
15-1 Characteristics of the Atmosphere • Layers • Mesosphere • Layer above the stratosphere • Coldest layer, -93˚C • Contains large wind storms • Winds will reach 320 km/hr
15-1 Characteristics of the Atmosphere • Layers • Ionosphere • Between the Mesosphere and Thermosphere • Area where gas particles will become electrically charged • Gives off different colors of light
15-1 Characteristics of the Atmosphere • Layers • Thermosphere • Layer above the mesosphere • Temperature will increase with altitude • Can reach 1,700˚C • Does not feel hot because particles are far apart
15-2 Heating of the Atmosphere • Energy • Radiation • The transfer of energy as electromagnetic waves • Most is reflected • Controls convection and conduction
15-2 Heating of the Atmosphere • Energy • Conduction • The transfer of thermal energy from one material to another by direct contact • Always moves from warm to cold areas
15-2 Heating of the Atmosphere • Energy • Convection • Transfer of thermal energy by the circulation or movement of a liquid or gas • Convection current • Process of warm air rising and cool air sinking in a circular motion
15-2 Heating of the Atmosphere • Greenhouse Effect • Where gases in the atmosphere trap thermal energy • Allows energy in but will not let it out • If out of balance Earth will heat up
15-3 Pressure and Winds • Air Movement • Wind • The movement of air • Created from a difference in pressure • Greater the difference the greater the speed • Forms because of the unequal heating of the Earth
15-3 Pressure and Winds • Air Movement • Pressure Belts • Warm air from the equator rises and cold air from the poles sinks • As air warms it creates low pressure • Creates convection cells • The circular patterns caused by the rising and sinking of air
15-3 Pressure and Winds • Air Movement • Coriolis Effect • Curving of wind by Earth’s rotation • N. Hemisphere curves to the right • S. Hemisphere curves to the left
15-3 Pressure and Winds • Wind Types • Local Winds • Move short distances and blow from any direction • Global Winds • A pattern of air circulation that moves across the Earth
15-3 Pressure and Winds • Wind Types • Trade Winds • Winds that blow from 30˚ latitude to the equator • Coriolis effect causes them to curve • Doldrums • Where the trade winds meet • Very little wind because of the warm rising air
15-3 Pressure and Winds • Wind Types • Westerlies • Wind belt between 30˚ and 60˚ latitude • Flow toward the poles in opposite direction of the trade winds • Polar Easterlies • Wind belt that extends from the poles to 60˚ latitude • Form from cold sinking air
15-3 Pressure and Winds • Wind Types • Jet Stream • Narrow belts of high-speed winds • Blows around the upper troposphere and lower stratosphere • Does not follow a regular path • Local winds • Influenced by geography • Differences between land and water
Chapter 16 Understanding Weather
16-1 Water in the Air • Weather • The condition of the atmosphere at a particular time and place • Water Cycle • Runoff • Trans/Evaporation • Condensation • Precipitation • Runoff
16-1 Water in the Air • Humidity • That amount of water vapor or moisture in the air • Depends on the temp. • Higher the temp the more water the air can hold • Relative humidity • The amount of moisture the air contains compared with the maximum amount it can hold at a temp
16-1 Water in the Air • Humidity • Measuring • Psychrometer • Used to measure relative humidity • Consists of 2 thermometers • One wet bulb • Will drop with less humidity • One dry bulb • Measures air temp
16-1 Water in the Air • Condensation • The process by which a gas becomes a liquid • Dew Point • The temp to which air must cool to be completely saturated
16-1 Water in the Air • Clouds • A collection of water droplets or ice crystals • Form from warm are rising and cooling • Water vapor collects on particles of ash and smoke
16-1 Water in the Air • Clouds • Cumulus • Puffy, white with a flat bottom • Cumulonimbus • Large cumulus clouds that produce thunderstorms
16-1 Water in the Air • Clouds • Stratus • Form in layers • Cover large areas • Caused by a gentle lifting of a large body of air • Nimbostratus • Dark clouds that produce continuous rain
16-1 Water in the Air • Clouds • Cirrus • Thin, feathery, white clouds at high altitudes • Form when wind is strong • Indicates approaching bad weather
16-1 Water in the Air • Clouds • Also Classified by the altitude at which they form • Cirro- • High clouds • Alto- • Middle clouds • Strato- • Low clouds
16-1 Water in the Air • Precipitation • Water the falls from the air to the Earth • 4 Forms • Rain • Snow • Sleet • Hail
16-1 Water in the Air • Precipitation • Snow • Forms when temp are cold enough to freeze water vapor • Can fall as snowflakes or ice crystals
16-1 Water in the Air • Precipitation • Sleet • Freezing rain • Forms when rain falls through a layer of freezing air • Water freezes on the way down
16-1 Water in the Air • Precipitation • Hail • Forms from up-drafts • Water falls but is taken back up in the air where it freezes • Continues to build until up-draft can’t carry it • Rain • Falling of water from the air
16-2 Air Masses and Fronts • Air Mass • A large body of air that has similar temperature and moisture throughout • Source Regions • Area where air mass gets it moisture and temp characteristics
16-2 Air Masses and Fronts • Air Mass • Cold Air Mass • Continental Polar • Develops over northern Canada • Extreme cold in winter and cool dry in summer • Maritime Polar • Forms over N. Pacific and N. Atlantic • Rain and snow in winter and cool foggy in summer
16-2 Air Masses and Fronts • Air Mass • Warm Air Masses • Maritime Tropical • Forms over N. Pacific, Gulf of Mexico, and N. Atlantic • Bring hot humid air in summer and mild cloudy in winter • Continental Tropical • Forms over N. Mexico and SW U.S. • Clear Dry weather
16-2 Air Masses and Fronts • Fronts • Boundary where 2 different air masses meet • 4 Types • Cold • Cold Air displaces warm air • Causes storms • Warm • Warm air displaces cold air • Brings drizzle
16-2 Air Masses and Fronts • Fronts • 4 Types • Occluded • Faster moving cold air overtakes a slower moving warm air mass • Cool temps with lots of precipitation • Stationary • Cold air mass meets a warm air mass with little horizontal motion • Same as warm front conditions
16-3 Severe Weather • Thunderstorms • Small intense weather systems that produce strong winds, heavy rain, lightning, and thunder • Occur along cold fronts • 2 conditions must be present • Air near Earth’s surface must be warm and moist • Atmosphere must be unstable
16-3 Severe Weather • Thunderstorm • Lightning • A large electrical discharge that occurs between two oppositely charge surfaces • Thunder • Energy causes air to expand rapidly and send out sound waves
16-3 Severe Weather • Severe Thunderstorms • Produce one or more of the following conditions • High winds • Hail • Flash floods • Tornadoes
16-3 Severe Weather • Tornadoes • A small, rotating column of air that has high wind speeds and low central pressure that touches the ground • Starts as funnel cloud that comes out of a cumulonimbus cloud • Wind avg. 120-180 km/h but can reach 500 km/h • Usually last for 8 km on avg.
16-3 Severe Weather • Tornadoes • 4 Steps to Create • Wind traveling in 2 different directions cause air layer to rotate • Updrafts cause rotating layer to turn vertical • Rotating column works downward to form funnel • Funnel touches ground
16-3 Severe Weather • Hurricanes • A large rotating tropical weather system with winds of at least 119 km/h • Called typhoons in the Pacific and Cyclones in the Indian Oceans • Form between 5˚ and 20˚ N and S Latitude • Range from 160 km to 1,500 km in diameter
16-3 Severe Weather • Hurricane Formation • Begins as a group of T-Storms over tropical water • Different directional winds cause rotation • Will grow as long as it’s over warm water
16-3 Severe Weather • Damage • Winds can reach speeds of 300 km/h • Storm Surge • A wall of water that builds up over the ocean due to winds • Range from 1-8 m high • Range from 65-160 km long • Causes massive flooding