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The Atmosphere Introduction to atmosphere, weather, and climate Where is the atmosphere? – Everywhere! Completely surrounds Earth February 20, 2010 What makes up the atmosphere? Makes life possible on Earth – Argon – Inert gas Importance of our atmosphere 1% Variable Gases – Influential for _________ & _________ ______________ ______________ 1. 2. 3. 4. – Source of all clouds and precipitation; heating/cooling – Absorbs infrared radiation = warms lower atmosphere 4 Layers of the Atmosphere Thermosphere It gets colder as you go up in the troposphere because you get farther from the earth, the main heat source. Stratosphere Tropopause Troposphere We live in the _________ 1 Troposphere Lowest region of the atmosphere Contains ½ of the Earth’ Earth’s atmosphere Temperature ____________ with an _________________ _____________ occurs in this layer Extends from surface to about 11 miles Depth of tropopause Between the troposphere & Stratosphere is the tropopause Height is variable Varies in time & place – – – – – Tropical regions Poles Summer Winter Warm/cold air masses Stratosphere Temperature ________ with an ____________________ – Called a __________________ Extends from about 11 miles to 30 miles Why is there a temperature inversion in the stratosphere? Mesosphere – – Temperature ________ with an _______________ Where meteors burn up while entering the Earth’s atmosphere 2 Thermosphere First exposed to the Sun's radiation and so is first heated by the Sun What is atmospheric pressure? – Air is so thin that a small increase in energy can cause a large increase in temperature – Taller the column of air above an object, the greater the air pressure exerted on that object Contains the ionosphere – Region of the atmosphere filled with charged particles – Makes radio communication possible Density & Pressure Air is highly compressible Lower layers of atmosphere are compressed by air above it – This compression increases pressure & density of the lower layers of the atmosphere Our atmosphere produces an infinite variety of conditions and phenomena know as weather What is the difference between weather and climate? Weather – Climate – Weather that we expect to occur – Based on long time average of day-to-day weather conditions, variations, and extremes Elements of weather & climate – Temperature, moisture content, pressure, and wind – The basic ingredients of weather and climate 3 Examples of Weather – Temperature, cloud cover, precipitation, humidity Climate: _________________________ 30 year average in U.S. precipitation temperature seasonal variations in monthly averages wind speed and direction cloud cover Use climograph to display climate data What kind of weather would you expect? January in Barrow, Alaska June in Mobile, Alabama Climograph What controls weather & climate? Meteorology condition of atmosphere at a given time for a given area temperature, pressure, wind, moisture Climatology usually over past 30 years Semipermanent attributes of Earth that influence climate & weather 1. 2. 3. 4. 5. 6. 7. 4 Latitude Most basic control of ___________ Land-Water Contrast – If this were the only control of temperature on Earth, then isotherms would run east to west – This means that land heat and cools quicker than water – This also means that it takes a lot of time and heat energy to change the temperature of water Temperature _________ as latitude ___________ – Because solar insolation decreases with an increase in latitude New Orleans, LA – Average January temp = 51.3 °F – Average July temperature = 81.9 °F Land-Water Contrast Fargo, ND – Average January temp = 5.9 °F – Average July temp = 71.1 °F Water has a much higher specific heat than land Fargo, ND has a 65.2 °F difference between January & July temperatures – Very continental climate, hot in the summer and very cold in the winter New Orleans, LA has a 30.6 °F difference between January & July temperatures – Temps are influenced by the Gulf of Mexico Wind Patterns & Air Masses Semipermanent pattern of major wind and pressure systems dominates the troposphere Wind Patterns & Air Masses Dominant wind direction influences local temperature patterns Dominant wind direction for midlatitudes is from the _________ – This means that air masses tend to move from the _____________ 5 Ocean Currents Ocean Currents Assist in heat transfer – Move warm water poleward & cool water toward the equator Warm currents are found off the eastern coasts of continents Cool currents occur off western coasts Altitude/Elevation Generally speaking, temperature decreases with increased elevation High elevation stations have a similar temperature pattern as nearby stations as a lower elevation Topographic Barriers Effect climate & weather by diverting wind flow Side of mountain range facing the wind is called the ______________ Side of mountain range that is sheltered is called the _____________ – Consistently cooler Storms Can affect a wide area or be localized Result from interactions among other climate controls 6 Atmosphere: blanket of air surrounding earth 1. 2. 3. Without our atmosphere: cold, quiet, cratered place Dynamic: currents and circulation cells Atmosphere important in equalizing temperature and pressure by transfer of heat, energy, and moisture around world The Sun & Insolation The Sun (cont.) The Sun Most important source of energy for Earth’ Earth’s atmosphere Provides an immense and continuous flow of radiant energy – Electromagnetic waves UV, visible, infrared all is shortwave (uv (uv & visible) Almost Dispersed in all directions .. Less than one billionth of total solar output reaches Earth’ Earth’s atmosphere How bright the sun shines Factors affecting intensity Driving force behind _________ and ____________ 1. Total insolation is a function of _________________ Controlled primarily by ___________ 7 1. Angle of the sun’s rays affects intensity of insolation Angle of incidence Latitudinal comparison Surface area covered (Latitude and season affect angle of sun’s rays) 2. Atmospheric transparency affects intensity of insolation How bright the sun shines Factors affecting intensity 1. Angle of the sun’s rays 2. 100% at top of atmosphere How bright the sun shines 5% scattered or reflected 30-60% reflected by clouds Factors affecting intensity 1. Angle of the sun’s rays 15% absorbed by molecules and dust 2. Atmospheric transparency 3. 80% can reach ground on clear day 5-20% absorbed by clouds 0-45% reaches ground on cloudy day 8 3. Altitude affects intensity of insolation Mt. Everest, 5.5 mi high How long the sun shines during the day Depends on _______ and ________ High-latitudes Duration of Insolation June Solstice Fall Equinox December Solstice N.Pole Spring Equinox 12 hrs. 24 hrs. 12 hrs. 0 hrs. N.Mid-Lat 12 hrs. ~15 hrs 12 hrs. ~9 hrs. Equator 12 hrs. 12 hrs. 12 hrs. 12 hrs. S.Mid-lat 12 hrs. ~9 hrs. 12 hrs. ~15 hrs S. Pole 12 hrs. 0 hrs. 12 hrs. 24 hrs. Mid-latitudes: sun never directly overhead Tropics: sun is directly overhead twice a year Low latitudes Mid-latitudes: sun never directly overhead High-latitudes TROPICS: insolation high year round due to high sun angle and constant duration Mid-latitudes: insolation highest at summer solstice due to higher sun angle and longer day, lowest at winter solstice due to low angle and short day High latitudes: insolation highest at summer solstice due to 24 hour duration low angle sun, extremely low to none at winter solstice Seasonal variation in insolation at top of atmosphere Equator Duration Poles Angle Total Duration Angle Total Spring 12 hrs. Equinox High High 12 hrs. Horizon Low Sum. 12 hrs. Solstice HighHigh- HighHigh- 24 hrs Low High Fall 12 hrs. Equinox High High 12 hrs. Horizon Low Winter 12 hrs. Solstice HighHigh- HighHigh- 0 hrs. Below horizon Zero 9 Insolation that reaches the Earth can be… 1. Total annual insolation __________________ 2. Proportion reflected = Does not heat Earth High albedo Dark surfaces are more efficient absorbers Low albedo Seasonality _________________________ Absorbed radiation heats the earth. The earth then radiates energy back out. Earth’s energy balance Earth radiates in longer wavelengths 90% of this radiation absorbed by atmosphere Greenhouse gases Clouds also absorb outgoing longwave energy There is a balance between the total amount of insolation received by Earth & atmosphere & total amount radiation returned to space Atmosphere is warm, therefore it also radiates energy Counter radiation directed back to Earth Net Radiation Incoming – Outgoing radiation energy How does heat move from one place to another? 1. 2. Highest at low latitudes = surplus energy Lowest at high latitudes = deficit of energy 3. 10 Conduction How can earth move energy from surplus to deficit areas? (Methods of heat transfer) 1. All bodies above -460°F (-273°C) (0° Kelvin) radiate energy. Heat that is transferred from one part of a stationary body to another when the two are in contact EarthEarth-air interface – Land heats up – transferred to lower atmosphere Lower body temperature, longer wavelength. Thermal infrared wavelength energy radiated by Earth heats troposphere. For this – only important at earth-air interface Convection Heat transferred from one point to another by a moving substance ConvectionVertical currents AdvectionHorizontal currents Temperature Measurement of sensible heat/energy Temperature is an expression of the degree of hotness or coldness of a substance There is a link between troposphere temperature and Earth surface conditions Temperature Depends On … 1. Insolation Intensity x Duration angle of sun’s rays latitude atmospheric transparency season altitude – The air temperature represents the balance between insolation and terrestrial radiation 11 Temperature depends on … Temperature depends on … 2. Reflectivity (albedo) of surface 3. Whether surface is land or water (continentality) Relative rates of heat flow into soil and water Relative rates of heat flow into soil and water Soil 5°C 10°C 20°C 40°C Water heats up (and cools down) slower than land Æ Most land has low albedo. It absorbs radiation and heats up CONTINENTALITY Why does water heat and cool slower than land? 1. 2. 3. 4. 5. 12
