Chapter 13- Atmosphere and Climate Change Weather- the state of the atmosphere at a certain place and moment. Climate- long –term prevailing weather conditions at a particular place . Chapter 13- Atmosphere and Climate Change

Comparing Weather and climate What is the weather like today in Grovetown? Describe the climate in Grovetown.

Factors that Determine Climate Latitude Atmospheric circulation patterns Oceanic circulation patterns Geography Solar activity Volcanic activity Distance from the Equator MOST IMPORTANT

Latitude: What is it? http://swapnil-exploringworld.blogspot.com/2011/01/aroundthe-world-brazil-part-3.html The distance from the equator measured in degrees north or south of the equator. Equator= 0° Latitude Northernmost latitude= 90 ° North latitude North Pole Southernmost latitude= 90 ° South latitude South Pole http://www.treeandeducation.in/2011/07/north-pole.html

Identifying Latitude Lines

Latitude: How does it influence climate? By the amount of solar energy an area of Earth receives Low latitudes- more solar energy Sunlight concentrated in a smaller area 12 hour days and nights at the Equator High temperatures year round No summers or winters High latitudes- Less solar energy Sunlight spreads over a further area 16 hour days during in summer and 8 hour days in winter.

Atmospheric Circulation Three properties Cold air sinks, it compresses and warms. More dense Warm air rises, expands and cools. Less dense Warm air holds more water vapor than cold air. Thus, when warm air cools the water vapor condenses into precipitation.

How does global atmospheric circulation develop? By the Earth’s rotation and because different latitudes receive different amounts of solar energy. Warm air holds large amounts of water. What is wind? The movement of air within the atmosphere Solar energy heats the ground. Causes warm air to rise Cool air moves in to replace the warm air

Formation of Wind

Global Circulation patterns Prevailing winds- winds that blow in one direction throughout the year. Due to the Earth’s rotation, Winds are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

Prevailing Winds Trade Winds blow in both hemispheres between 30° north and south latitudes of the equator. Blow northeast in the Northern Hemisphere and southeast in the Southern Hemisphere Westerlies blow between 30° and 60°North and South latitudes. Blow Southeast in the Northern Hemisphere and Northeast in the Southern Hemisphere Polar easterlies blow from the poles to 60 north and south latitudes

Oceanic Circulation Patterns Ocean currents have a great effect on climate because water absorbs a lot of heat. Ocean currents caused mostly by wind and the rotation of the Earth.

El Niñ0- Southern Oscillation (ENSO) cycle El Niño- Water in the Eastern Pacific ocean is warmer. Warm water pushed eastward by wind Normal conditions- warm water is pushed westward by wind Produces an increase in rainfall in southern half of U.S. Drought in Indonesia and Australia. La Niña- Water in the eastern Pacific Ocean is cooler than usual. Remember: El Niño= Warm phase of ENSO cycle La Niña= Cool phase of ENSO cycle

Topography Mountains and mountain ranges influence rain distribution. Sierra Nevada mountains of California.

Warm air from Pacific Ocean blows East and hits the mountains, and rises. As the air rises it cools, causing it to rain on the western side. By the time it reaches the eastern side the air is dry . Rain Shadow effect

Solar Influence When the sun releases solar maximum there is an increase in ultraviolet radiation. The increase in radiation warms the lower atmosphere and surface of the Earth and produces more ozone.

Volcanoes Volcanic eruptions release sulfur dioxide which reacts with water vapor and dust. This reaction forms a bright layer of haze that reflects sunlight to decrease global temperatures.

Seasonal Changes in Climate What causes the seasons? Caused by the tilt in the Earth’s axis. This tilt changes the angle at which the sun’s rays strike the Earth as the Earth orbits around the sun. What happens during summer in the Northern Hemisphere? Northern Hemisphere tilts towards the sun and receives direct sunlight. Hours of daylight is greatest during the summer. When it is summer in the Southern Hemisphere, what season is it in the Northern Hemisphere? Winter Tilted away from the sun and receives a lot less sunlight

The Ozone Layer A layer in the stratosphere where ozone is highly concentrated. Absorbs most UV radiation from the sun. Ozone- is a molecule made up of 3 oxygen atoms (O3) The Ozone shield acts like a sunscreen for the Earth’s inhabitants.

Chemicals Responsible for Depletion Chlorofluorocarbons (CFC’s): human-made chemicals Considered miracle chemicals Non poisonous Nonflammable Noncorrosive Used in coolants refrigerators propellant in spray cans

Chlorofluorocarbons At the Earth’s surface CFC’s are chemically stable which means they do not break down or react. Takes a period of 10-20 years for CFC’s to reach the atmosphere In the stratosphere, UV rays break CFC’s apart CFC’s destroy and break down the protective ozone

How Do CFC’s Destroy Ozone

The Ozone Hole Researchers state that the ozone layer above the South Pole has thinned by 50-98%. Ozone hole- a thinning of stratospheric ozone that occurs at the poles during the spring. As much as 70% of the ozone layer can be destroyed during the spring. Long time to regenerate the ozone layer if destroyed

How does it affect us? (Humans) An influx of UV radiation is dangerous to living things because it can damage our DNA. More susceptible to skin cancer.

How does it affect Plants and Animals? Amphibians lay eggs in shallow water. High levels of UV radiation damage DNA and disrupts embryonic development. UV radiation damages plants by interfering with photosynthesis. Results in lower crop yields

How does it affect Plants and Animals? Kills phytoplankton that live near the surface of the ocean. Due to increased UV radiation Loss of phytoplankton could disrupt the ocean’s food web, and increase the amount of CO2 in the atmosphere.

What Can We Do to Protect Our Ozone Layer? Limit the production of CFC’s Use alternative, environmentally safe chemicals to replace CFC’s. Nations agree to ban CFC use. Led to Montreal Protocol Montreal Protocol(1987) Developed countries agreed to eliminate most CFC’s by 1995 U.S pledged to ban all substances that threaten the ozone layer by 2000

The Greenhouse Effect Sunlight penetrates the atmosphere and warms the Earth. Heat bounces off the Earth’s surface, some escapes into space. Most is absorbed by gases and warms the air.

Greenhouse Gases Definition- Gases that absorb and radiate heat. Include •water vapor • carbon dioxide •CFC’s •Methane •Nitrous oxide CO2 and water vapor account for most of the heat absorption

Carbon Dioxide Levels Most CO2 in the air is dissolved in the ocean or is used in plants for photosynthesis. As a result, carbon dioxide levels fluctuate with the seasons. CO2 levels decrease in summer and increase during winter months.

Rising Carbon Dioxide Levels CO2 levels are rising in ways other than seasonal fluctuations. CO2 levels have risen more than 20% the past 50 years. This increase is due to the burning of fossil fuels

Correlations Is there a correlation between rising carbon dioxide levels and rise in global temperatures? Many say yes, and many say no. Need more research to justify

Global Warming Slow rise in Earth’s surface temperature Scientists see a connection between an increase in greenhouse gases and an increase in temperature

Consequences of a Warmer Earth Change in weather patterns Glacial retreat, and melting of polar ice caps. Rise in sea levels Some ecosystems will adapt to changes in climate.

Consequences of a Warmer Earth

Consequences of a Warmer Earth Warmer climate means warmer oceans and an increase in hurricane activity Some regions may have more rainfall causing floods. Others may have a significant decrease in rainfall creating drought conditions

Human Health Problems Increase in heat related deaths Heat Exhaustion Heat Stroke Increased concentrations of ground-level ozone Allergy seasons extended Insect vectors spread diseases

Agriculture •High temperatures could result in decrease in crop yields •Droughts •Demand for irrigation and depletion of aquifers.

Effects on Plants and Animals Alter range of plant species Lose diversity Shift geological range of animals Reduction of zooplankton Destroy coral reefs

Recent Findings IPCC –network of 2500 leading climatologists. They say that the Earth’s surface increased by 0.6 °C Snow cover has decreased Sea level has risen Greenhouse gas levels have increased Predict that human activity will alter the Earth’s atmosphere

Reducing the Risk Kyoto protocol Reduce carbon dioxide emissions in developing and developed countries Reforestation