Earth’s Atmosphere

Composition of Earth’s Atmosphere Atmosphere surrounding Earth is a mixture of solids, liquids, and gases. Nitrogen is the most common gas at 78%. Oxygen makes up 21 % Water vapor can range from 0-4%. Meaning if water vapor is high then the percentage of the other gases are slightly lower. Dust and ice are two common solids found in the atmosphere. Common liquids in the atmosphere is water. Water is the only substance that exists as a solid, liquid, and gas in Earth’s atmosphere.

Smog Is a mixture of compounds that include sulfur, nitrogen, and oxygen. The burning of coal, gasoline, and other fossil fuels will produce sulfur and nitrogen. Type of pollution. Smoke-like haze that hangs over cities and towns.

Structure of the Atmosphere Five main layer. Each with unique characteristics. Troposphere Stratosphere Mesosphere Thermosphere Exosphere

Troposphere Layer we live in. Closest to the ground Contains 75% of all atmosphere gases, as well as dust, ice, and liquid. Layer where weather, clouds, and smog occur.

Stratosphere Lies above the troposphere. Ozone layer exists.

Other Layers Beyond the stratosphere are the mesosphere, thermosphere, and exosphere. One important layer in the thermosphere is the ionosphere. Ionosphere is a layer of electrically charged particles. They can interfere with radio waves. Exosphere uppermost part of Earth’s Atmosphere. There is NO clear boundary between the atmosphere and space.

Atmospheric Pressure and Temperature Coldest layer of air is Mesosphere and the warmest layer is the troposphere. In general, atmospheric pressure is greatest near Earth’s surface and decreases as you move out toward space. Atmospheric pressure is caused by atoms and molecules of gas are pushed together because of weight of the atmosphere above them. Cold air is more dense than warm air, therefore, has higher pressure.

Ozone Layer 30km above your head. Can’t feel, smell, or observe it. Is a shield between you and harmful energy coming from the sun. A compound whose molecules are composed of three oxygen atoms bonded together. Located in the stratosphere. Absorbs most of the ultraviolet radiation. Ultraviolet radiation comes from the sun and causes sunburn. Radiation causes cancer and other health problems. Ozone layer is disappearing, there is a large hole over Antarctica and a small hole over the North Pole. Chlorofluorocarbon molecules destroy ozone molecules. They are found in refrigerants, aerosol sprays, and foam products.