CHAPTER 15AIR, WEATHER,

AND CLIMATE

Abby Searfoss

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 concentrationsAerosols- small liquid droplets

suspended in the air

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

Solar Radiation Solar radiation is reflected by surfaces with a high albedo such

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

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 currentsWhen 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

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

Seasonal winds Some areas receive seasonal winds and

rains that are vital for the ecosystems and human life thereTropical 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

Frontal systems Front- boundary between two air masses of different

temperature and density Cold front- cooler air

displaces warmer airOften 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 andprecipitation

Cyclonic storms Caused by low-pressure cells (rising warm air) over

warm tropical oceansThis happens because of the Coriolis effect

Winds near the center of the swirling air masses reach hundreds of km/hr causing huge destructionCalled hurricanes, typhoons, or cyclones

Tornadoes- swirling funnel clouds that form over landStrong updrafts can create hail too

Downbursts- supercells not organized enough to create tornadoes but can generate straight-line winds over 160 km/hr

Catastrophic Climate Changes Many different theories:

Big changes after interaction of unrelated eventsBig changes after periodic patterns

Milankovitch cycles- periodic shifts in the earth’s orbit andtilt 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

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

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

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

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

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 watersCarbon management

Individual countries, cities, and towns have come up with their own ways to help the environment and reduce the threat of global warming

Works cited http://auth.mhhe.com/biosci/pae/environmentalscience/olc_link

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#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/db220a

2ad.jpg http://www.companysj.com/v244/cuban-hurricane.jpg http://upload.wikimedia.org/wikipedia/commons/5/5a/Milankovit

ch-cycles_hg.png http://www.globalwarmingart.com/images/thumb/a/ae/Global_

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