Presentation on theme: "The Atmosphere (Abridged)"— Presentation transcript:
1 The Atmosphere (Abridged) Purpose: The purpose of this presentation is to provide APES students with important information on the atmosphere.Objective: At the end of this presentation students will have generated notes necessary to understand key processes in the Earth’s atmosphere.
2 The Atmosphere-history 3.2 billion years ago (bya) atmosphere mostly steam and CO2 (Life begins in sea)bya photosynthetic bacteria (cyanobacteria) began producing oxygenmya ozone levels in stratosphere sufficient to protect land plants from UV radiation.
3 The Atmosphere-current composition Around 1% Ar20.01-4% H2O0.037 CO2
4 The Atmosphere-current composition The Greenhouse Effect- Natural warming effect of the troposphere1. sunlight hits the Earth’s surface turning into infrared (heat) radiation2. heat risessome escapes into spacesome heats greenhouse gases emitting infrared radiation which warm the troposphere+
5 The Atmosphere-current composition Major greenhouse gases:water vapor (primary)CO2O3 (ozone)CH4 (methane)N2O (nitrous oxide)CFCs (chlorofluorocarbons)
6 The Atmosphere-current composition Mean global temperature14.53oC or 58.14oF ( )14.0oC or 57.2oF ( )(Source-18oC or 0oF without greenhouse effect
7 The Atmosphere-Climate Climate: Regional patterns of atmospheric conditions-mainly influenced by average temperature and precipitation-globally follows a cyclic pattern+ glacial periods lasting around 100,000 yrs+ interglacial periods lasting around 10,000 yrs+ Holocene epoch—nearing end of interglacial period
8 The Atmosphere-climate Factors that affect global climateshape of the Earth’s orbit (eccentricity)“wobble” of the Earth’s axis (precession)changes in the tilt of the Earth’s axis (obliquity)volcanic activitychanges in solar outputatmospheric composition
9 The Atmosphere-climate Factors that affect regional climateuneven heating of the Earth’s surface (varies by latitude and season)rotation of the Earthocean currentsmountainsaltitudetilt of the Earth
10 The Atmosphere-factors that affect regional climate Uneven heating of the Earth’s surfaceConsistent, year-round heating at equatorMore seasonal variation as latitude increasesUneven heating produces atmospheric areas of low pressure (less dense, rising air) and high pressure (more dense, falling air.)Pattern alternates about every 30 degree change in latitude (p. 125)
11 The Atmosphere-factors that affect regional climate: Earth’s rotation Coriolis Effect—The apparent deflection of a moving object due to the motion of the Earth underneath it
12 The Atmosphere-factors that affect regional climate: ocean currents Water’s high specific heat causes it to gain and lose heat slower than land massesOceans produce milder climatesChanges in density due to temperature differences and the Earth’s rotation produce ocean circulation patternsEurope is warmer than it should be due to warm ocean currents
13 The Atmosphere-factors that affect regional climate: ocean currents
14 The Atmosphere-factors that affect regional climate: mountains Mountains force air masses to rise as they pass across themRising air cools and moisture condenses producing precipitation on the “windward’ sideDescending air on the “leeward” side has less moisture producing areas of lower precipitationRain shadow effect
15 The Atmosphere-factors that affect regional climate: mountains
16 The Atmosphere-factors that affect regional climate: altitude Average temperature decreases about 3oF for every 1000 feet in altitude Barrons p. 117
17 The Atmosphere-factors that affect regional climate: tilt of the Earth The Seasons!
18 The Atmosphere-weather Weather-The short-term conditions in the troposphere at a location.Includes atmospheric conditions such as- temperature- pressure- relative humidity- sunshine- cloud cover- wind direction and speed
19 The Atmosphere-weather: temperature Measure of kinetic energyDifferences produced by uneven heating of Earth’s surfaceMaps of areas with the same temperatures are called isotherms
21 The Atmosphere-weather: temperature Normally troposphere gets cooler with altitudeTemperature inversion--a layer or warmer air above cooler surface air- subsidence inversionlarge mass of warmer air moves into a region, floats over top of stationary cooler air- radiation inversionat night air near the ground cools faster than air above
25 The Atmosphere-weather: temperature Warm Front—leading edge of advancing mass of warm air-less dense so rises up over colder air-more gradual lifting produces thickening clouds and longer periods of rain
27 The Atmosphere-weather: temperature (note symbols)
28 The Atmosphere-weather: clouds Condensation of water vapor in rising air due to lower temperatures.Atmospheric conditions determine cloud typeCloud names indicate appearance and altitude
29 The Atmosphere-weather: Clouds Cirrus Clouds:-High altitude-Thin and wispy
30 The Atmosphere-weather: Clouds Stratus Clouds-lower altitude-layered and sheetlike
31 The Atmosphere-weather: Clouds Cumulus Clouds-Low to medium altitude-Flat bottom and fair weather-Cumulonimbus are thunderstorm clouds
32 The Atmosphere-weather: Pressure Earth’s gravity pulling down on molecules in the atmosphere creates atmospheric pressureAtmospheric pressure at sea level is:- 760 mm of Hgin. of Hgpsimillibar
33 The Atmosphere-weather: Pressure Maps of areas with the same barometric pressure are called isobarsAreas of low pressure bring cloudy rainy weather. Counterclockwise (NH) (cyclone)Areas of high pressure usually indicate clear weather. Clockwise (NH) (anticyclone)Air moves from areas of high pressure into areas of low pressure—wind!
36 The Atmosphere-weather: Jet Stream Narrow, fast-moving wind current in the upper tropospherePosition usually coincides in part with the regions of greatest storminess in the lower troposphereAlso called polar jet stream, because of the importance in moving cold, polar air.
40 Atmospheric-Oceanic Interactions: ENSO El Nino-A warming of the surface water of the eastern and central Pacific Ocean, occurring every 4 to 12 years and causing unusual global weather patterns.trade winds that usually push warm surface water westward weaken, allowing the warm water to pool as far eastward as the western coast of South America.
43 Atmospheric-Oceanic Interactions: La Nina Cooling of the surface water of the eastern and central Pacific Ocean, causing similar, generally opposite disruptions to global weather patterns.Trade winds blow more strongly than usual, pushing the sun-warmed surface water farther west and increasing the upwelling of cold water in the eastern regions.
44 Atmospheric-Oceanic Interactions: El Nino vs. La Nina
47 Typical vs. El Nino vs. La Nina Winds off the western coast of equatorial South America blow east to west, pushing surface waters west.Cooler deeper waters rise (upwelling) to replace moving surface water, bringing nutrients to the surface, increasing fish populations.El NinoWinds off the western coast of equatorial South America lessen, stop or start to blow west to east.Warmer surface waters deepen as they “run into” western South America. Deep nutrients do not rise, decreasing fish populations.La NinaWinds off the western coast of equatorial South America strengthen, blowing east to west, pushing surface waters west.Surface waters off of the west coast of equatorial South America cool due to increased upwelling. Increased fish populations.
48 Typical vs. El Nino vs. La Nina Normal rainfall in western South America, southeastern Asia, eastern Africa, southeastern South America and southeastern U.S.Normal rainfall in southern Africa, Australia, eastern South America, northwestern and northeastern Canada and U.S.El NinoIncreased rainfall in western South America, southeastern Asia, eastern Africa, southeastern South America and southeastern U.S.Less rainfall/drought in southern Africa, Australia, eastern South America, northwestern and northeastern Canada and U.S.La NinaDecreased rainfall in western South America, southeastern Asia, eastern Africa, southeastern South America and southeastern U.S. Increased tornadoes in the U.S.More rainfall in southern Africa, Australia, eastern South America, northwestern and northeastern Canada and U.S.
49 Typical vs. El Nino vs. La Nina Normal number of Atlantic and Pacific hurricanesNormal temperatures in eastern Asia, northwestern Canada and U.S. and northeastern Canada and U.S.El NinoFewer Atlantic and more Pacific hurricanesWarmer temperatures in eastern Asia, northwestern Canada and U.S. and northeastern Canada and U.S.La Nina“Sometimes” more Atlantic and fewer Pacific hurricanesCooler winter temperatures in southeastern and southwestern U.S.Warmer winter temperatures in north central U.S.
50 Don’t Forget the 5-Question Quick Quiz on Tuesday