Earth’s Atmosphere

Key Idea #17 The Earth’s atmosphere is a mixture of gases and water vapor and has different physical and chemical properties at different elevations.

What is the Atmosphere?

Earth’s atmosphere is a thin layer of gases that surrounds the earth. is dry air made up of 78% Nitrogen 21% Oxygen 1% trace gases and dust particles trace gases include argon, carbon dioxide, neon, helium, methane, krypton, and hydrogen.

The combination of gases in Earth’s atmosphere makes conditions on earth suitable for living things.

Earth’s atmosphere contains oxygen and other gases that living things need to live. traps energy from the sun and keeps most of Earth’s surface warm enough for water to exist as a liquid. protects living things from the sun’s radiation. protects Earth’s surface from being hit by most meteors.

Pollutants are harmful substances in the Air (atmosphere) Water (hydrosphere) Land (geosphere)

Most air pollution is due to the release of particles and gases when fossil fuels are burned. Fossil fuels include coal oil gasoline diesel fuel

The main cause of air pollution comes from sources that burn fossil fuels: automobiles fuel consumption in factories and buildings heating systems coal-burning power plants Consumers Energy lantic_Region/Sources_of_Air_PollutionWSC72DDCF9-1_En.htm

Fossil fuels are being depleted slowly because of constant use. Fossil fuels are not renewable. Once they’re gone, they're gone. sciencewithme.com

Burning fossil fuels releases carbon dioxide (CO 2 ) into the air which some scientists believe may be contributing to global warming.

Burning fossil fuels also causes sulfur dioxide gas and nitrogen oxide gas to form in the atmosphere causing acid rain.

Natural sources of sulfur dioxide include volcano eruptions, biological decay and forest fires. Natural sources of nitrogen oxides include volcanoes, oceans, biological decay and lightning strikes. FYI:

FYI: Acid Rain forms when nitrogen oxides and sulfur dioxides combine with water in the air to form nitric acid and sulfuric acid. Rain, snow, sleet, and fog carry these two acids from the air to trees, lakes, and buildings.

Acid rain damages plants, causing a loss of habitat which threatens or endangers species. pictures.html&usg=__czDpnP54W-khkK1G8AJO2ohh7ZY=&h=291&w=495&sz=35&hl=en&start=55&itbs=1&tbnid=ghX- ecM4MXGPJM:&tbnh=76&tbnw=130&prev=/images%3Fq%3Dair%2Bpollution%2Bimages%26start%3D40%26hl%3Den%26sa%3DN%26gbv%3D2%26ndsp%3D20%26tbs%3Disch:1

Acid rain can kill trees by burning new growth as it first sprouts, but more damaging are the metals that the trees absorb through their roots. Acidic precipitation frees up aluminum and other metals that are found naturally in the soil, changing the chemical composition into something the trees take through their roots. As a result, the Spruce Fir forests of the high peaks in North Carolina are dying from their own form of clogged arteries. FYI:

Air pollution also causes smog which irritates breathing passages in animals, including humans. harms plants, and damages rubber, paint, and some plastics. Note: Smog is formed from the words smoke and fog.

FYI: Photochemical smog is a brownish haze that is formed when nitrogen oxides and other pollutants react with each other in the presence of sunlight.

SOURCE : ENERGY INFORMATION ADMINISTRATION -- DEPARTMENT OF ENERGY -- KIDS HOME PAGE Energy Information Administration, Annual Energy Review 2007, June The National Energy Education Development Project, Intermediate Energy Infobook, 2007.ENERGY INFORMATION ADMINISTRATION

Our Restless Atmosphere

The atmosphere has different properties at different elevations. At higher elevations the air pressure is lower. atmosphere gets thinner. density of the air is lower. temperature of the air is generally colder.

Air (Atmospheric) Pressure Air has mass, takes up space, and exerts pressure. Air pressure is the result of the weight of a column of air pushing down on an area. We don’t feel air pressure because the molecules in air push in all directions. A barometer is used to measure changes in air pressure. The higher you go up in altitude the atmosphere is thinner and the air pressure is lower.

The atmosphere is thinner at higher elevations because the particles are more spread out. The concentration of oxygen per cubic meter at sea level (0 feet) is about 21%. As you go up in altitude, the total amount of oxygen per cubic meter is still 21% but there are fewer oxygen molecules to breath in each cubic meter of air than there are at sea level. At an elevation of 80 km (50 miles) there is very little air.

FYI: Note the percent of oxygen at sea level compared to the percent of oxygen at the top of Mount Everest.

Altitude also affects density. If there are more molecules in the air then there is more air pressure and the air is denser. As you go up through the atmosphere, the density of the air decreases (gets lower) as the air pressure decreases. The density of the air is lower because there are fewer molecules in a given volume of air. Density = Mass/Volume 100g/cm³ = 100g/1cm³ 15g/cm³ = 15g/1cm³

The four main layers of the atmosphere include: troposphere: where Earth’s weather occurs. stratosphere: contains the ozone layer. mesosphere: most meteoroids burn up here as a result of the heat created by collisions with some of the billions of gas particles contained there. thermosphere: contains communication satellites and extends into outer space. dlweather/hydrosphere_and_atmosphere.htm&usg=__oXFA_FxBdShERULdyjqhuFqfprk=&h=340&w=520&sz=5&hl=en&start=2&itbs=1&tbnid=HWvHX3EOASqrEM:&tbnh=86&tbnw=131&prev=/image s%3Fq%3Dearth%2527s%2Batmosphere%26hl%3Den%26gbv%3D2%26tbs%3Disch:1

FYI: Ozone in the Stratosphere is a natural and necessary component. Acts as a UV shield by absorbing the harmful ultraviolet light from the sun, protecting life on Earth from its effects.

FYI: Layers of the atmosphere in miles

The layers of the atmosphere are classified according to changes in temperature (see pgs ). FYI: The temperature of the air decreases or increases depending on layer you are in. The stratosphere gets hotter the higher you go because ozone absorbs energy from the sun and converts it to heat, but it is still colder than Earth’s average temperature of 13°- 15°C. The temperature in the mesosphere decreases as you move higher in the atmosphere.

FYI: The upper level of the thermosphere is hot because energy from the sun hits it first and nitrogen and oxygen convert the energy to heat. The temperature is high because the gas molecules are moving very fast. However, you would not feel this as warmth because the molecules are spaced so far apart. An ordinary thermometer would show a temperature well below 0° C because it would not detect the molecules energy.

Weather Instruments Thermometer: Temperature Wind Vane: Wind Direction Wind Scale: Wind Speed Psychrometer: Relative Humidity Rain Gauge: Precipitation Cloud Chart: Cloud Type

Example: Weather Data Chart: May 4, 2009 Class 1st2nd4th5th6th Time 9:20 am10:35 am11:09 a.m.12:50 p.m.2:01 pm Temperature °F and °C 62F 17C 70F 22C 69 f 21 c 75f 26c 75f 26c Barometric Pressure 1013 mb inches 1016 mb in mb in mb inch 1014 mb 29.93in Humidity 53%49%48%47%48% Precipitation Type none Precipitation Amount none Wind Direction SE EastSE Wind Speed mph4-7 mph Cloud Type cirrostratuscirrus Cloud Cover (none, partly, mostly, all) Partlypartly