Preview Section 1 Characteristics of the Atmosphere Section 2 Atmospheric Heating Section 3 Global Winds and Local Winds Section 4 Air Pollution Concept Mapping

Section 1 Characteristics of the Atmosphere Bellringer List the ways that the atmosphere is different from outer space. Write your list in your science journal.

Objectives Describe the composition of Earth’s atmosphere. Section 1 Characteristics of the Atmosphere Objectives Describe the composition of Earth’s atmosphere. Explain why air pressure changes with altitude. Explain how air temperature changes with atmospheric composition. Describe the layers of the atmosphere.

Properties of Air A. Air is a gas. B. It takes up space. C. It has mass. D. It exerts pressure. E. It expands when heated and contracts when cooled. F. Hot air is less dense than cold air so hot air will weigh less than cold air. G. Air has velocity.

The Composition of the Atmosphere Section 1 Characteristics of the Atmosphere The Composition of the Atmosphere The atmosphere is made up mostly of nitrogen gas. Oxygen makes up a little more than 20% of the atmosphere. Water in the form of a gas called water vapor along with tiny particles such as dirt, salt from the oceans, and ash from volcanoes make up part of the remaining atmosphere.

Atmospheric Pressure and Temperature Section 1 Characteristics of the Atmosphere Atmospheric Pressure and Temperature The atmosphere is held around the Earth by gravity. Gravity pulls gas molecules in the atmosphere toward the Earth’s surface, causing air pressure, which is the measure of the force with which air molecules push on a surface. As altitude increases, air pressure decreases. Air temperature changes as altitude increases. Depending on the amount of gases that absorb solar energy, the temperature can increase or decrease in the layers of the atmosphere. When a gas absorbs energy from the sun, the air temperature goes up.

Layers of the Atmosphere Section 1 Characteristics of the Atmosphere Layers of the Atmosphere There are four main layers of the atmosphere. The divisions between the layers are based on how each layer’s temperature changes with height. The Troposphere: The Layer in Which We Live The lowest layer of the atmosphere, lies next to the Earth’s surface Weather occurs in this layer Densest layer of the atmosphere Both air temperature and air pressure decrease as you move higher in this layer

The Stratosphere: Home of the Ozone Layer Section 1 Characteristics of the Atmosphere The Stratosphere: Home of the Ozone Layer The atmospheric layer above the troposphere The gases in this layer do not mix, they are layered Temperature increase due to ozone which absorbs energy from the sun (ultraviolet energy) Pressure decreases The Mesosphere: The Middle Layer the middle layer of the atmosphere. It is the coldest layer. Temperature decreases

The Thermosphere: The Edge of the Atmosphere Section 1 Characteristics of the Atmosphere The Thermosphere: The Edge of the Atmosphere The uppermost atmospheric layer temperature increases pressure decreases has the highest temperatures The Ionosphere: Home of the Auroras In the upper mesosphere and the lower thermosphere nitrogen and oxygen atoms absorb harmful solar energy. Auroras occur Reflects radio waves

Section 1 Characteristics of the Atmosphere

Section 2 Atmospheric Heating Bellringer How is food heated in an oven? How is food heated on a range top?   Record your response in your science journal.

Objectives Describe what happens to solar energy that reaches Earth. Section 2 Atmospheric Heating Objectives Describe what happens to solar energy that reaches Earth. Summarize the processes of radiation, thermal conduction, and convection. Explain the relationship between the greenhouse effect and global warming.

Energy in the Atmosphere Section 2 Atmospheric Heating Energy in the Atmosphere Radiation: Energy Transfer by Waves The Earth receives energy from the sun by radiation. Radiation is the transfer of energy as electromagnetic waves. Not all of the radiation from the sun reaches Earth’s surface. Much of it gets absorbed by the atmosphere. As solar energy is absorbed by air, water, and land, it turns into heat energy. This energy causes winds, the water cycle, ocean currents, and changes in the weather. Some of the radiation is scattered and reflected by clouds and gases.

Energy in the Atmosphere Section 2 Atmospheric Heating Energy in the Atmosphere Conduction: Energy Transfer by Contact Thermal conduction is the transfer of thermal energy through a material. It is always transferred from warm to cold areas. Convection: Energy Transfer by Circulation Convection is the transfer of thermal energy by the circulation or movement of a liquid or gas. As air warms it becomes less dense and rises. As air cools, it becomes more dense and sinks. This cycle of warm air rising and cool air sinking causes a circular movement of air called a convection current.

Section 2 Atmospheric Heating

Energy in the Atmosphere, continued Section 2 Atmospheric Heating Energy in the Atmosphere, continued The Greenhouse Effect and Life on Earth Earth’s atmosphere acts like the walls of a greenhouse which allow solar energy to enter but prevents thermal energy from escaping. Sunlight travels through the atmosphere easily, but heat does not. Gases in the atmosphere absorb heat energy coming from Earth then radiate it back to Earth’s surface warming the planet. This process is known as the greenhouse effect.

Section 2 Atmospheric Heating

Energy in the Atmosphere, continued Section 2 Atmospheric Heating Energy in the Atmosphere, continued The Radiation Balance: Energy In, Energy Out The amount of energy Earth receives and the amount of energy returned to space must be approximately equal. Greenhouse Gases and Global Warming Some scientists think that an increase of greenhouse gases in the atmosphere may be the cause of global warming.

Section 3 Global Winds and Local Winds Bellringer Write a poem about moving air. The poem should include an explanation of why air moves. Record your response in your science journal.

Section 3 Global Winds and Local Winds Objectives Explain the relationship between air pressure and wind direction. Describe global wind patterns. Explain the causes of local wind patterns.

Section 3 Global Winds and Local Winds Why Air Moves Air Rises at the Equator and Sinks at the Poles As the cold air sinks, it creates areas of high pressure around the poles. This cold polar air then flows toward the equator. Pressure Belts Are Found Every 30º Convection cells are separated by pressure belts, bands of high and low pressure.

Section 3 Global Winds and Local Winds

Why Air Moves, continued Section 3 Global Winds and Local Winds Why Air Moves, continued The Coriolis Effect The apparent curving of the path of currents due to the Earth’s rotation is called the Coriolis effect.

Section 3 Global Winds and Local Winds

Section 3 Global Winds and Local Winds Polar Easterlies are the wind belts that extend from the poles to 60° latitude in both hemispheres. Westerlies are the wind belts found between 30° and 60° latitude in both hemispheres. Trade Winds are the winds that blow from 30° latitude almost to the equator in both hemispheres.

Global Winds, continued Section 3 Global Winds and Local Winds Global Winds, continued The Doldrums The trade winds of the Northern and Southern Hemispheres meet in an area around the equator called the doldrums. The Horse Latitudes At about 30° north and 30° south latitude, sinking air creates an area of high pressure called the horse latitudes. Jet Streams are narrow belts of high-speed winds that blow in the upper troposphere and lower stratosphere.

Section 3 Global Winds and Local Winds

Section 3 Global Winds and Local Winds Local winds generally move short distances and can blow from any direction. Mountain and valley breezes are examples of local winds caused by an area’s geography. Sea and land breezes are affected by temperature.

Section 3 Global Winds and Local Winds

Section 4 Air Pollution Bellringer Examine the filter mask. Make a list of three situations in which one might wear such a mask. Write your answers in your science journal.

Objectives Compare primary and secondary air pollution. Section 4 Air Pollution Objectives Compare primary and secondary air pollution. Identify the major sources of pollution. Explain the effects of the ozone hole. List five effects of air pollution on the human body. Identify ways to reduce air pollution.

Section 4 Air Pollution Primary Pollutants Pollutants that are put directly into the air by human or natural activity are primary pollutants. Primary pollutants from human sources include carbon monoxide, dust, smoke, and chemicals from paint and other substances.

Section 4 Air Pollution Secondary Pollutants Pollutants that form when primary pollutants react with other primary pollutants or with naturally occurring substances, such as water vapor, are secondary pollutants. Smog is a secondary pollutant that forms when ozone and vehicle exhaust react with sunlight, as shown in the next slide.

Secondary Pollutants, continued Section 4 Air Pollution Secondary Pollutants, continued

Sources of Human-Caused Air Pollution Section 4 Air Pollution Sources of Human-Caused Air Pollution Industrial Air Pollution Many industrial plants and electric power plants burn fossil fuels, such as coal, to produce energy. Burning some types of coal without pollution controls can release large amounts of air pollution. Indoor Air Pollution Sometimes, the air inside a building can be more polluted than the air outside. Sources of indoor air pollution are shown on the next slide.

Indoor Air Pollution, continued Section 4 Air Pollution Indoor Air Pollution, continued

Section 4 Air Pollution Acid Precipitation Rain, sleet or snow that contains a high concentration of acids is called acid precipitation. Acid Precipitation and Plants Acid precipitation can cause the acidity of soil to increase. This process, called acidification, changes the balance of a soil’s chemistry and negatively affects plants.

Acid Precipitation, continued Section 4 Air Pollution Acid Precipitation, continued The Effects of Acid Precipitation on Forests In some areas of the world, acid precipitation has damaged large areas of forest. Acid Precipitation and Aquatic Ecosystems If acid precipitation increases the acidity of a lake or stream, aquatic plants, fish, and other aquatic organisms may die.

Section 4 Air Pollution The Ozone Hole The Earth’s protective ozone layer is thinning over the Arctic and Antarctic regions. These ozone holes allow more UV radiation, which damages genes and can cause skin cancer, to reach the earth’s surface. Cooperation to Reduce the Ozone Hole In 1987, many nations agreed to reduce the use of CFCs, the chemicals that cause ozone depletion. Because CFCs remain active for 60 to 120 years, however, it will take many years for the ozone layer to recover.

Ozone and Ozone Holes Section 4 Air Pollution Click below to watch the Visual Concept. Visual Concept

Air Pollution and Human Health Section 4 Air Pollution Air Pollution and Human Health Short-Term Effects of air pollution, such as coughing, headaches, and eye irritation can be avoided by staying indoors on days when the air quality is poor. Long-Term Effects of air pollution, such as lung cancer, are particularly dangerous because they may not be noticed until many years after exposure.

Cleaning up Air Pollution Section 4 Air Pollution Cleaning up Air Pollution The EPA sets air quality standards to protect against the effects of air pollution on human health as well as on crops, vegetation, and buildings. Controlling Air Pollution from Industry The Clean Air Act requires many industries to use pollution-control devices.

Reducing Air Pollution Section 4 Air Pollution Reducing Air Pollution The Allowance Trading System Companies are fined for exceeding limits and rewarded for low emissions. Reducing Motor Vehicle Emissions The EPA requires car makers to meet a certain standard for vehicle exhaust. New technology to reduce emissions is under development. People can make choices to reduce air pollution, such as car-pooling and conserving electricity.

The Atmosphere Concept Mapping Use the terms below to complete the concept map on the next slide. radiation nitrogen pressure troposphere mesosphere oxygen atmosphere thermosphere

The Atmosphere

The Atmosphere