Chapter 15 Air, Weather, and Climate

1. Abby Searfoss Chapter 15Air, Weather, and Climate

2. The Atmosphere Basics • Weather- daily temperature and moisture conditions of an area • Climate- long term weather patterns of an area • Both weather and climate are controlled by the composition and behavior of the troposphere • Early atmosphere was made of hydrogen and helium but now our clean air is composed of nitrogen and oxygen with low water vapor concentrations • Aerosols- small liquid droplets suspended in the air

3. 4 Layers of the Atmosphere • Troposphere- layer of air closes to earth’s surface- air constantly circulates in convection currents which move heat and moisture • 75% of total mass of atmosphere • Stratosphere- no water vapor but huge amounts of ozone- warmer atmosphere because of UV radiation • Mesosphere- middle layer • Thermosphere- heated gases

4. Solar Radiation • Solar radiation is reflected by surfaces with a high albedosuch as clouds and gases • Surfaces that absorb energy have low albedo and appear much darker and heat the surface such as asphalt and black soil • Greenhouse effect- atmosphere transmits sunlight while trapping heat inside • Infrared is the most common light to reach and be absorbed in the troposphere • Eventually all energy is reradiated back into space

5. Currents, winds, and more • Water vapor contains latent heat which is stored energy that cannot be detected by ordinary senses • When the warm air rises above the denser air  convection currents • When air rises, surface air pressure is low • Air always wants to move from high pressure areas to low pressure areas  wind! • Air cools as it rises and as it cools, water condenses which, along with condensation nuclei, forms clouds, rain, or snow

6. Currents, winds, and more • Wind movements are controlled by the earth’s spin due to the Coriolis effect- winds curve along with the earth • Jet streams- hurricane force winds that circle the earth and have a huge impact on weather • Ocean currents result from wind pushing on the water surface causing deeper water to replace it

7. Seasonal winds • Some areas receive seasonal winds and rains that are vital for the ecosystems and human life there • Tropical and subtropical regions have distinct rainy and dry seasons because of intense solar heating and evaporation shifts • Monsoons- seasonal reversals of wind patterns caused by the different heating and cooling rates

8. Frontal systems • Front- boundary between two air masses of different temperature and density • Cold front- cooler air displaces warmer air • Often accompanied by heavy surface winds and harmful storms • Warm front- warmer air slides up over cool air parcels • Creates a long wedge-shape with a broad band of clouds and precipitation

9. Cyclonic storms • Caused by low-pressure cells (rising warm air) over warm tropical oceans • This happens because of the Coriolis effect • Winds near the center of the swirling air masses reach hundreds of km/hr causing huge destruction • Called hurricanes, typhoons, or cyclones • Tornadoes- swirling funnel clouds that form over land • Strong updrafts can create hail too • Downbursts- supercells not organized enough to create tornadoes but can generate straight-line winds over 160 km/hr

10. Catastrophic Climate Changes • Many different theories: • Big changes after interaction of unrelated events • Big changes after periodic patterns • Milankovitch cycles- periodic shifts in the earth’s orbit and tilt changing the distribution of sunlight which results in global climate change • Evidence has come up that climate change can occur more rapidly and often than previously thought

11. El Niño/ Southern Oscillations • Describes a connection between the ocean and atmosphere that affects weather patterns around the world • Huge pool of warm water in Pacific moving back and forth between Indonesia and South America pushed by surface currents  every 3 to 5 years the Indonesian low collapses causing a surge of the warm water back east across the Pacific- huge increase in surface water temperature • El Niño- name of event (the Christ child) often around Christmas time • La Niña- intervening years • El Niño Southern Oscillation (ENSO)- cycle • Global Effects • Heavy rains from California to the Midwest • Drought in Australia and Indonesia • Pacific Decadal Oscillation (PDO)- large pool of warm water moving across North Pacific every 30 years making waters warmer or cooler than average

12. Human effects • Intergovernmental Panel on Climate Change (IPCC)- panel of scientists assessing the current state of human impacts on climate change • On global warming the panel has said: “We have altered the chemical composition of the atmosphere through the buildup of greenhouse gases-primarily carbon dioxide, methane, and nitrous oxide.” • Huge CO2 increases from burning fossil fuels and biomass, and making cement • Aerosols reflect sunlight and cool surface air temperatures but are temporary

13. Global Climate Change • Over the past 100 years, global surface air temperatures have increased a little less that 1ºC • As the climate warms, infectious diseases will become more common and many plants and animals species will be forced out of their natural habitats • Rates of precipitation, as well as droughts have also increased in respective regions • Rising sea levels and heavy storms will heavily reduce coastlines

14. Kyoto Protocol • In December 1997, 160 nations signed a treaty at the global climate conference • CO2, methane, and nitrous oxide emissions were to be reduced about 5 percent (depending on the nation’s output) from 1990 to 2012 • Three other greenhouse gases: hydrofluorocarbons, perfluorocarbons, and sulfur hexaflouride were to be reduced also • The United States never ratified the treaty so we are technically not required to honor the commitments

15. Controlling Emissions • Britain: natural gas for coal, promote energy efficiency, raise gasoline tax • Germany: reduced CO2 emissions by 10% by substituting gas for coal • Renewable energy sources, conservation • Denmark: 20% of electricity from wind generators • Plant trees, inject CO2 into underground rock or deep ocean waters • Carbon management • Individual countries, cities, and towns have come up with their own ways to help the environment and reduce the threat of global warming

16. Works cited • http://auth.mhhe.com/biosci/pae/environmentalscience/olc_linkedcontent/cunningham06es/cs6_17.htm • http://science.howstuffworks.com/weather3.htm • http://www.odec.ca/projects/2005/stro5c0/public_html/greenhouse_effect.jpg • http://www.energyquest.ca.gov/story/chapter01.html • http://www.fas.org/irp/imint/docs/rst/Sect14/FIG07_014A.jpg • http://science.nationalgeographic.com/science/photos/climate/#5402_600x450.jpg • http://www.fas.org/irp/imint/docs/rst/Sect14/Sect14_1c.html • http://www.fas.org/irp/imint/docs/rst/Sect14/Sect14_1d.html • http://photo.accuweather.com/photogallery/2006/6/500/db220a2ad.jpg • http://www.companysj.com/v244/cuban-hurricane.jpg • http://upload.wikimedia.org/wikipedia/commons/5/5a/Milankovitch-cycles_hg.png • http://www.globalwarmingart.com/images/thumb/a/ae/Global_Warming_Predictions_Map.jpg/350px-Global_Warming_Predictions_Map.jpg • http://www.global-greenhouse-warming.com/images/KyotoProtocol.jpg