The Atmosphere. Importance of our. 4 Layers of the Atmosphere. Introduction to atmosphere, weather, and climate. What makes up the atmosphere?

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1 The Atmosphere Introduction to atmosphere, weather, and climate Where is the atmosphere? Everywhere! Completely surrounds Earth February 20, 2010 What makes up the atmosphere? Argon Inert gas 1% Variable Gases Influential for & Source of all clouds and precipitation; heating/cooling Absorbs infrared radiation = warms lower atmosphere Importance of our atmosphere Makes life possible on Earth Layers of the Atmosphere Thermosphere Stratosphere It gets colder as you go up in the troposphere because you get farther from the earth, the main heat source. Tropopause Troposphere We live in the 1

2 Troposphere Depth of tropopause Lowest region of the atmosphere Contains ½ of the Earth s s atmosphere Temperature with an occurs in this layer Extends from surface to about 11 miles 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

3 Thermosphere First exposed to the Sun's radiation and so is first heated by the Sun Air is so thin that a small increase in energy can cause a large increase in temperature Contains the ionosphere Region of the atmosphere filled with charged particles Makes radio communication possible What is atmospheric pressure? Taller the column of air above an object, the greater the air pressure exerted on that object 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

4 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? Climograph January in Barrow, Alaska June in Mobile, Alabama 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

5 Latitude Most basic control of If this were the only control of temperature on Earth, then isotherms would run east to west Temperature as latitude Because solar insolation decreases with an increase in latitude Land-Water Contrast Water has a much higher specific heat than land 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 New Orleans, LA Average January temp = 53 F Average July temperature = 89 F Fargo, ND Average January temp = 5.9 F Average July temp = 71 F Land-Water Contrast 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

6 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 Consistently cooler 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 Storms Can affect a wide area or be localized Result from interactions among other climate controls 6

7 Atmosphere: blanket of air surrounding earth 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 Most important source of energy for Earth s atmosphere The Sun (cont.) Provides an immense and continuous flow of radiant energy Electromagnetic waves UV, visible, infrared Almost all is shortwave (uv( & visible) Dispersed in all directions.. Less than one billionth of total solar output reaches Earth s s atmosphere How bright the sun shines Driving force behind and Total insolation is a function of Controlled primarily by Factors affecting intensity 7

8 Angle of the sun s rays affects intensity of insolation Latitudinal comparison Angle of incidence Surface area covered (Latitude and season affect angle of sun s rays) Atmospheric transparency affects intensity of insolation How bright the sun shines Factors affecting intensity Angle of the sun s rays 100% at top of atmosphere 5% scattered or reflected 15% absorbed by molecules and dust 80% can reach ground on clear day 5-20% absorbed by clouds 30-60% reflected by clouds 0-45% reaches ground on cloudy day How bright the sun shines Factors affecting intensity Angle of the sun s rays Atmospheric transparency 3. 8

9 3. Altitude affects intensity of insolation Mt. Everest, 5.5 mi high How long the sun shines during the day Depends on and Duration of Insolation High-latitudes N.Pole Spring Equinox June Solstice 24 hrs. Fall Equinox December Solstice 0 hrs. Mid-latitudes: sun never directly overhead N.Mid-Lat Equator ~15 hrs ~9 hrs. Tropics: sun is directly overhead twice a year Low latitudes S.Mid-lat ~9 hrs. ~15 hrs S. Pole 0 hrs. 24 hrs. Mid-latitudes: sun never directly overhead High-latitudes TROPICS: insolation high year round due to high sun angle and constant duration Seasonal variation in insolation at top of atmosphere Duration Equator Angle Total Duration Poles Angle Total 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 Spring Equinox Sum. Solstice High High- High High- 24 hrs Horizon Low Low High High latitudes: insolation highest at summer solstice due to 24 hour duration low angle sun, extremely low to none at winter solstice Fall Equinox Winter Solstice High High- High High- 0 hrs. Horizon Below horizon Low Zero 9

10 Insolation that reaches the Earth can be Total annual insolation Proportion reflected = Does not heat Earth High albedo Low albedo Dark surfaces are more efficient absorbers Seasonality Absorbed radiation heats the earth. The earth then radiates energy back out. Earth radiates in longer wavelengths 90% of this radiation absorbed by atmosphere Greenhouse gases Clouds also absorb outgoing longwave energy Earth s s energy balance 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 How does heat move from one place to another? Incoming Outgoing radiation energy Highest at low latitudes = surplus energy Lowest at high latitudes = deficit of energy 3. 10

11 How can earth move energy from surplus to deficit areas? (Methods of heat transfer) All bodies above -460 F (-273 C) (0 Kelvin) radiate energy. Lower body temperature, longer wavelength. Thermal infrared wavelength energy radiated by Earth heats troposphere. Conduction Heat that is transferred from one part of a stationary body to another when the two are in contact Earth-air air interface Land heats up transferred to lower atmosphere For this only important at earth-air interface Convection Heat transferred from one point to another by a moving substance Convection- Vertical currents Advection- Horizontal 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 The air temperature represents the balance between insolation and terrestrial radiation Temperature Depends On Insolation Intensity x Duration angle of sun s rays atmospheric transparency altitude latitude season 11

12 Temperature depends on Reflectivity (albedo) of surface Temperature depends on 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 Most land has low albedo. It absorbs radiation and heats up Water heats up (and cools down) slower than land CONTINENTALITY Why does water heat and cool slower than land?