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Download Intro and Composition-Structure of the Atmosphere
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OVERVIEW: 1) Earth as a system 2) Weather elements 3) Atm composition 4) Atm structure Earth’s Atmosphere: Composition and Structure GEG 104 Weather & Climate •Earth’s Major Subsystems: Spheres are inter-dependently linked Boundaries are not distinct Solar energy drives all external processes 71+% of surface covered with water ATMOSPHERE 50% of surface covered with clouds BIO HYDROSPHERE The Big Blue Marble LITHOSPHERE Weather is All About DYNAMICS… SUN Weather is the short-term local conditions of the atmosphere Climate is the long-term average weather conditions within a larger region Gradients drive weather processes: z z Water Cycle: Linking Atmosphere and Hydrosphere Uneven distribution of heat, water, and pressure Vertical gradient, latitudinal gradient, land/sea contrast “If you don’t like the weather, wait five minutes and it will change…” 1 Elements of Weather and Storms Weather Tools Heat Human Observation Humidity Direct Observation z Pressure z z Wind Cloud Cover z Indirect Observation z z Precipitation z z Differences in temperature, humidity, & pressure drive all weather processes Thermometer Psychrometer Barometer Anemometer Radar Visible Satellite Imagery Infrared Satellite Imagery Water Vapor Imagery Every Breath You Take: Composition of the Lower Atmosphere: 78% Nitrogen 0.93% Argon 0.07% Other 21% Oxygen 0.93% Argon 0 - 4% Water Vapor Trace: z 0.037% CO2 z 0.000004% Ozone z 0.000001% Particles z 0.00000002% CFCs 21% Oxygen 78% Nitrogen Composition of the Atmosphere: Significance of Water Vapor Volume (0 - 4%) varies by: z z z z Elevation Latitude Season Local conditions Abundant in troposphere (1.5 billion billion gallons) Source of clouds & precip. Readily absorbs heat as a “Greenhouse Gas” 2 Structure of the Atmosphere Blanket of air surrounding Earth Structure of the Atmosphere: Atmospheric Pressure No distinct outer boundary (transition to space) 5,600 trillion tons of air pulled down by gravity exerts tremendous force in all directions 5,600 trillion tons of air held to Earth by gravity Force exerted at sea level averages: z Approximately 300 miles thick (480 km) z But, 99% of atmosphere is within 19 miles of surface z Mass, density, and pressure greatest at surface z 14.7 psi at sea level z Mass, density, and pressure decrease rapidly with altitude z 1013.25 millibars (mb) z 29.92 inches of Hg Stratified into layers defined by thermal differences z Ex: Tropopause is boundary b/n troposphere/stratosphere Structure of the Atmosphere: Pressure decreases rapidly with altitude Troposphere vs. Stratosphere Vertical Temperature Gradients (differences) Warm air rises in UNSTABLE troposphere, causing clouds, wind, precip. and storms Development of Clouds & T-storm 3 Troposphere Surface layer z 7 mi. average thickness z 5 mi. near poles z 12 mi. near equator Stratosphere Second layer up z Ozone layer z 80-90% of all atmospheric mass 7 to 30 mi. altitude absorbs UV radiation Warmed “ground up” by surface re-radiation Warmed “top down” by ozone layer absorbing heat Temperature decreases as altitude increases Temperature increases as altitude increases Unstable; warm air rises causing clouds & storms Water present and plays important role z z Temperature “inversion” Stable conditions; warm air above cold air “No” water and “No” weather & climate All weather & climate (wind, rain, storms…) 4
