The Atmosphere Earth’s Thin Blue Skin

The Atmosphere The atmosphere is a mixture of gases that surrounds a planet, such as Earth. Nitrogen(78.4%) oxygen (21%) carbon dioxide (0.03%) Argon (1%) Water vapor (up to 4%) Other gasses

The Atmosphere The atmosphere insulates Earth’s surface. Greenhouse effect- keeps Earth’s temperatures in the zone for life

Layers of The Atmosphere The atmosphere is divided into four layers based on temperature changes that occur at different distances above the Earth’s surface. The Troposphere The Stratosphere The Mesosphere The Thermosphere

The Troposphere The troposphere is the lowest layer of the atmosphere in which temperature drops at a constant rate as altitude increases. We live in the troposphere. This is the part of the atmosphere where weather conditions exist. The troposphere is Earth’s densest atmospheric layer and extends to 18 km above Earth’s surface.

The Stratosphere The stratosphere is the layer of the atmosphere that lies immediately above the troposphere and extends from about 10 to 50 km above the Earth’s surface. Contains ozone layer.

Ozone Ozone is a gas molecule that is made up of three oxygen atoms. Absorbs UV radiation, it reduces amount of UV radiation that reaches the Earth. UV radiation that does reach Earth can damage living cells. OZONE HAS NOTHING TO DO WITH GLOBAL WARMING!!!!!

The Mesosphere The layer above the stratosphere is the mesosphere. This layer extends to an altitude of about 80 km. This is the coldest layer of the atmosphere where temperatures have been measured as low as –93ºC.

The Thermosphere The atmospheric layer located farthest from Earth’s surface is the thermosphere. Here, nitrogen and oxygen absorb solar radiation resulting in temperatures measuring above 2,000 ºC. The air in the thermosphere is so thin that air particles rarely collide, so little heat is transferred, and would therefore not feel hot to us.

Heating of the Atmosphere About half of the solar energy that enters the atmosphere passes through it and reaches the Earth’s surface, while the rest of the energy is absorbed or reflected in the atmosphere by clouds, gases, and dust or it is reflected by Earth’s surface.

Heating of the Atmosphere The Earth does not continue to get warmer because the oceans and the land radiate the absorbed energy back into the atmosphere. Because the ocean both absorbs and releases heat slower than land, the temperature of the atmosphere changes more slowly. This is one reason the temperature in cities is higher that the temperature in the surrounding countryside. Heating of the air is not even everywhere!

Movement of Air in the Atmosphere As a current of air, warmed by Earth’s surface, rises into the atmosphere, it begins to cool, and eventually becomes more dense than the air around it and sinks. This current then moves back toward the Earth until heated and less dense and then begins to rise again. The continual process of warm air rising and cool air sinking moves air in a circular motion is called a convection current.

Weather Temporary behavior of atmosphere (what ’ s going on at any certain time) Small geographic area Can change rapidly

Climate Long-term behavior of atmosphere (100+ years) Large Large geographic area slow Very slow to change

Air Masses body of air with a certain temperature and moisture level As it moves, the characteristics of an air mass change and so does the weather

Fronts places where air masses meet 4 Types: Warm, Cold, Occluded, Stationary Each kind can bring different kinds of weather

Fronts Cold Front – cold, dense air moves into a region occupied by warmer air, leads to heavy downpours and gusty winds Warm Front – warm air moves into an area occupied by cooler air, Brings warmer temperatures and precipitation,

Fronts Occluded Front – an active cold front takes overtakes a warm front; complex weather pattern Stationary Front – flow of air is neither toward cold or warm air mass. Occluded Front Stationary Front

Pressure Differences Move Masses Air has mass. The weight of air at the surface causes pressure. pressure. Warm air rising creates a low pressure. Cold air sinking creates a high pressure.

Low pressure Moisture of rising air condenses causing clouds. Wind moves counter clockwise.

High Pressure Cool dry air sinks causing clear weather. Air moves clockwise. Usually light winds Represented with an H on the mapthe map

Moisture in the air Warm air can hold more moisture than cold air. Relative humidity is how close to SATURATED the air is. Relative humidity Dew point is the temperature the moisture in the air will condense to liquid water. Higher dew point= more humid. (Above

Dew point and human comfort Dew point F°Human Comfort Over 80 Severely high. Even deadly for asthma related illnesses 75-79Extremely uncomfortable 70-74Quite uncomfortable 65-69Somewhat uncomfortable 60-64Ok, but feels humid 55-59Comfortable 50-54Very comfortable Less than 49Dry

Human Impact on the Atmosphere

Air pollution Human activity produces two main types of air pollutant: particulates – Tiny particles suspended in air (e.g. smoke) and are usually produced by the combustion of fossil fuels. noxious gases – Include carbon dioxide (CO 2 ), sulfur dioxide (SO 2 ) and nitrogen oxides (NO x ). Air pollution has been a major problem since the Industrial Revolution of the late 18 th Century, and has been made worse by humans ’ reliance on burning fossil fuels for energy. Air pollution, global warming, acid rain, damage to the ozone layer and smog. Each of these has serious implications for the environment and human health.

Greenhouse Effect The greenhouse effect is the warming of the surface and lower atmosphere of Earth that occurs when carbon dioxide, water vapor, and other gases in the air absorb and reradiate infrared radiation. Without the greenhouse effect, the Earth would be too cold for life to exist.

Greenhouse Effect The gases in the atmosphere that trap and radiate heat are called greenhouse gases. The most abundant greenhouse gases are water vapor, carbon dioxide, methane, and nitrous oxide, although none exist in high concentrations. The quantities of carbon dioxide and methane in the atmosphere vary considerable as a result of natural and industrial processes.

Global warming and greenhouse gases One of the greatest threats caused by air pollution is global warming. Global warming is caused by a build-up of greenhouses gases, which leads to an increase in the Earth ’ s temperature. Other effects include bizarre weather patterns, and melting of polar ice caps Key greenhouses gases include: carbon dioxide methane water vapour nitrous oxide

Acid Precipitation Caused by the release of sulfur dioxide and nitrogen oxide from factories Effects include soil erosion, death of animals and vegetation, erosion of buildings

Ozone Depletion Caused by the use of coolants and aerosol cans Effects include increased UV radiation, skin cancer and eye disorders

Smog Smog is a mixture of air pollutants and particulates that is sometimes found in the lower levels of the atmosphere. It has a distinctive brownish haze. Smog can reach dangerous levels in built- up areas, causing irritation to the eyes and lungs.