Presentation on theme: "The Atmosphere (Abridged) Purpose: The purpose of this presentation is to provide APES students with important information on the atmosphere. Objective:"— Presentation transcript:
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.
The Atmosphere-history 3.2 billion years ago (bya) atmosphere mostly steam and CO 2 (Life begins in sea) bya photosynthetic bacteria (cyanobacteria) began producing oxygen mya ozone levels in stratosphere sufficient to protect land plants from UV radiation.
The Atmosphere-current composition 78 % N 2 21 % O 2 Around 1% Ar % H 2 O CO 2
The Atmosphere-current composition The Greenhouse Effect - Natural warming effect of the troposphere 1. sunlight hits the Earth’s surface turning into infrared (heat) radiation 2. heat rises some escapes into space some heats greenhouse gases emitting infrared radiation which warm the troposphere +
The Atmosphere-current composition Major greenhouse gases: -water vapor (primary) -CO 2 -O 3 (ozone) -CH 4 (methane) -N 2 O (nitrous oxide) -CFCs (chlorofluorocarbons)
The Atmosphere-current composition Mean global temperature o C or o F ( ) 14.0 o C or 57.2 o F ( ) (Source -18 o C or 0 o F without greenhouse effect
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
The Atmosphere-climate Factors that affect global climate shape of the Earth’s orbit (eccentricity) “wobble” of the Earth’s axis (precession) changes in the tilt of the Earth’s axis (obliquity) volcanic activity changes in solar output atmospheric composition
The Atmosphere-climate Factors that affect regional climate uneven heating of the Earth’s surface (varies by latitude and season) rotation of the Earth ocean currents mountains altitude tilt of the Earth
The Atmosphere-factors that affect regional climate Uneven heating of the Earth’s surface Consistent, year-round heating at equator More seasonal variation as latitude increases Uneven 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)
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
The Atmosphere-factors that affect regional climate: ocean currents Water’s high specific heat causes it to gain and lose heat slower than land masses Oceans produce milder climates Changes in density due to temperature differences and the Earth’s rotation produce ocean circulation patterns Europe is warmer than it should be due to warm ocean currents
The Atmosphere-factors that affect regional climate: ocean currents
The Atmosphere-factors that affect regional climate: mountains Mountains force air masses to rise as they pass across them Rising air cools and moisture condenses producing precipitation on the “windward’ side Descending air on the “leeward” side has less moisture producing areas of lower precipitation Rain shadow effect
The Atmosphere-factors that affect regional climate: mountains
The Atmosphere-factors that affect regional climate: altitude Average temperature decreases about 3 o F for every 1000 feet in altitude Barrons p. 117
The Atmosphere-factors that affect regional climate: tilt of the Earth The Seasons!
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
The Atmosphere-weather: temperature Measure of kinetic energy Differences produced by uneven heating of Earth’s surface Maps of areas with the same temperatures are called isotherms
The Atmosphere-weather: temperature
Normally troposphere gets cooler with altitude Temperature inversion--a layer or warmer air above cooler surface air - subsidence inversion large mass of warmer air moves into a region, floats over top of stationary cooler air - radiation inversion at night air near the ground cools faster than air above
The Atmosphere-weather: temperature
Cold Front—leading edge of advancing mass of cold air -more dense so slides under warmer air lifting it -rising warm air produces thunderheads and rainstorms
The Atmosphere-weather: temperature- Cold Front
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
The Atmosphere-weather: temperature- Warm Front
The Atmosphere-weather: temperature (note symbols)
The Atmosphere-weather: clouds Condensation of water vapor in rising air due to lower temperatures. Atmospheric conditions determine cloud type Cloud names indicate appearance and altitude
The Atmosphere-weather: Clouds Cirrus Clouds: -High altitude -Thin and wispy
The Atmosphere-weather: Clouds Stratus Clouds -lower altitude -layered and sheetlike
The Atmosphere-weather: Clouds Cumulus Clouds -Low to medium altitude -Flat bottom and fair weather -Cumulonimbus are thunderstorm clouds
The Atmosphere-weather: Pressure Earth’s gravity pulling down on molecules in the atmosphere creates atmospheric pressure Atmospheric pressure at sea level is: mm of Hg in. of Hg psi millibar
The Atmosphere-weather: Pressure Maps of areas with the same barometric pressure are called isobars Areas 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!
The Atmosphere-weather: Pressure
The Atmosphere-weather: Jet Stream Narrow, fast-moving wind current in the upper troposphere Position usually coincides in part with the regions of greatest storminess in the lower troposphere Also called polar jet stream, because of the importance in moving cold, polar air.
The Atmosphere-weather: Jet Stream
Atmospheric-Oceanic Interactions: El Nino- Southern Oscillation (ENSO) Normal conditions in eastern equatorial Pacific Ocean
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.
Atmospheric-Oceanic Interactions: ENSO
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.
Atmospheric-Oceanic Interactions: El Nino vs. La Nina
Typical vs. El Nino vs. La Nina Typical 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 Nino Winds 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 Nina Winds 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.
Typical vs. El Nino vs. La Nina Typical 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 Nino Increased 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 Nina Decreased 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.
Typical vs. El Nino vs. La Nina Typical Normal number of Atlantic and Pacific hurricanes Normal temperatures in eastern Asia, northwestern Canada and U.S. and northeastern Canada and U.S. El Nino Fewer Atlantic and more Pacific hurricanes Warmer temperatures in eastern Asia, northwestern Canada and U.S. and northeastern Canada and U.S. La Nina “Sometimes” more Atlantic and fewer Pacific hurricanes Cooler winter temperatures in southeastern and southwestern U.S. Warmer winter temperatures in north central U.S.
Don’t Forget the 5-Question Quick Quiz on Tuesday