The Air Around You Air Quality Air Pressure Layers of the Atmosphere
The Air Around You - Vocabulary Weather – The condition of Earth’s atmosphere at a particular time and place. Atmosphere – The layer of gases that surrounds Earth. Ozone – A form of oxygen that has three oxygen atoms in each molecule instead of the usual two. Water vapor – Water in the form of a gas.
The Air Around You – Main Ideas Earth’s atmosphere makes conditions on Earth suitable for living things. Earth’s atmosphere is made up of nitrogen, oxygen, carbon dioxide, water vapor, and many other gases, as well as particles of liquids and solids.
The Air Around You – Guiding Questions Describe two ways in which the atmosphere is important to life on Earth. What are the four most common gases in dry air? Why are the amounts of gases in the atmosphere usually shown as percentages of dry air?
Air Quality - Vocabulary Pollutants – Harmful substances in the air, water, or soil. Photochemical smog – A brownish haze that is a mixture of ozone and other chemicals, formed when nitrogen oxides, hydrocarbons, and other pollutants react with each other in the presence of sunlight. Acid rain – Rain that contains more acid than normal.
Air Quality – Main Ideas Most air pollution is the result of burning fossil fuels such as coal, oil, gasoline, and diesel fuel. Nitrogen oxides, hydrocarbons, and other air pollutants react with one another in the presence of sunlight to form a mix of ozone and other chemicals called photochemical smog Acid rain forms when nitrogen oxides and sulfur oxides combine with water in the air to form nitric acid.
Air Quality – Guiding Questions How is most air pollution produced? Name two natural and two artificial sources of particles in the atmosphere. How is photochemical smog formed? What kinds of harm does it cause? What substances combine to form acid rain?
Air Pressure - Vocabulary Density – The amount of mass of a substance to a given volume. Pressure – The force pushing on an area or surface. Air pressure – A force that is the result of the weight of a column of air pushing down on an area. Barometer – An instrument used to measure changes in air pressure.
Air Pressure - Vocabulary Mercury barometer – An instrument that measures changes in air pressure, consisting of a glass tube partially filled with mercury, with its open end resting in a dish of mercury. Air pressure pushing on the mercury in the dish forces the mercury in the tube higher. Aneroid barometer – An instrument that measures changes in air pressure without using a liquid. Changes in the shape of an airtight metal box cause a needle on the barometer dial to move. Altitude - Elevation above sea level.
Air Pressure Properties of air include mass, density, and air pressure. Air pressure is the result of the weight of a column of air pushing down on an area. Air pressure is measured with mercury barometers and aneroid barometers. Air pressure decreases as altitude increases. As air pressure decreases, so does density.
Air Pressure – Guiding Questions How does increasing the density of a gas affect its pressure? Describe how a mercury barometer measures air pressure. Why is the air at the top of a mountain hard to breathe?
Layers of the Atmosphere - Vocabulary Troposphere – The lowest layer of Earth’s atmosphere, where weather occurs. Stratosphere – The second-lowest layer of Earth’s atmosphere; the ozone layer is located in the upper stratosphere. Mesosphere – The middle layer of Earth’s atmosphere; the layer in which most meteoroids burn up. Thermosphere – The outermost layer of Earth’s atmosphere.
Layers of the Atmosphere - Vocabulary Ionosphere – The lower part of the thermosphere, where electrically charged particles called ions are found. Aurora borealis – A colorful, glowing display in the sky caused when particles from the sun strike oxygen and nitrogen atoms in the ionosphere; also called the Northern Lights. Exosphere – The outer layer of the thermosphere, extending outward into space.
Layers of the Atmosphere The thermosphere is composed of the ionosphere (80-550 km) and the exosphere (above 550 km) Mesosphere (50-80 km) Stratosphere (12-50 km) Troposphere (0-12 km)
Layers of the Atmosphere – Main Ideas The four mail layers of the atmosphere are classified according to changes in temperature. These layers are the troposphere, the stratosphere, the mesosphere, and the thermosphere. Rain, snow, storms, and most clouds occur in the troposphere. Ozone in the stratosphere absorbs energy from the sun.
Layers of the Atmosphere – Main Ideas Most meteoroids burn up in the mesosphere, producing meteor trails. The aurora borealis occurs in the ionosphere. Communications satellites orbit Earth in the exosphere.
Layers of the Atmosphere – Guiding Questions Describe one characteristic of each of the four main layers of the atmosphere. What is a shooting start? In which layer of the atmosphere would you see it? What is the aurora borealis? In which layer of the atmosphere does it occur?