Presentation on theme: "1 Chapter 11 Atmosphere. 2 I. Atmospheric Basics 1. The atmosphere is combined with several gasses. 2. About 99% of the atmosphere is composed of nitrogen."— Presentation transcript:
2 I. Atmospheric Basics 1. The atmosphere is combined with several gasses. 2. About 99% of the atmosphere is composed of nitrogen and oxygen, the remaining 1% small amounts of argon, hydrogen, carbon dioxide, water vapor and other gasses.
3 3. The amount of water vapor in the atmosphere at any given time or place changes constantly. It can be as much as 4% of the atmosphere or as little as almost zero. 4. The level of both carbon dioxide and water vapor are critical because they play an important role in regulating the amount of energy the atmosphere absorbs.
4 5. Water vapor is the source of clouds, rain and snow. 6. The atmosphere also contains solids in the form of tiny particles of dust and salt. Dust is carried into the atmosphere by wind.
6 B. Ozone 1. Another component of the atmosphere, ozone, (O3) is a gas formed by the addition of a third oxygen atom to an oxygen molecule. 2. It is important because it absorbs ultraviolet radiation from the Sun.
9 C. Structure of the atmosphere 1. The atmosphere is made up of several different layers. 2. The layer closest to Earth ’ s surface, the troposphere, contains most of the mass of the atmosphere, including water vapor. This is the layer in which most weather takes place and most air pollution collects.
10 3. Above the tropopause is the stratosphere, a layer made up primarily of concentrated ozone. 4. Above the stratopause is the mesosphere. There is no concentrated ozone in the mesosphere, so the temperature decreases once again
11 5. The thermosphere contains only a minute portion of the atmosphere ’ s mass. 6. The ionosphere is part of the thermosphere. It is made up of electrically charged particles and layers of progressively lighter gasses.
12 7. The exosphere is the outer layer of Earth ’ s atmosphere. Light gases such as helium and hydrogen are found in this layer.
22 3. Convection is the transfer of energy by the flow of heated substance.
23 II. States of atmosphere A. Temperature verse heat. 1. Temperature is a measurement of how rapidly or slowly molecules move around. More molecules are faster-moving molecules in a given area generate a higher temperature.
24 2. Heat is the transfer of energy that occurs because of a difference in temperature between substances. 3. Temperature can be measured in degrees Fahrenheit or degrees Celsius or in Kelvin ’ s.
26 4. Another atmospheric measurement is the dew point. The dew point is the temperature to which air must be cooled at constant pressure to reach saturation. 5. Saturation is the point at which the air holds as much water vapor as it possibly can.
27 6. Condensation occurs when matter changes state from a gas to a liquid.
30 B. Vertical Temperature changes 1. The height at which condensation occurs is called lifted condensation level (LCL) 2. Above the LCL, air becomes saturated and cools more slowly. 3. The rate at which saturated air-cools is called the moist adiabatic lapse rate.
31 C. Air pressures 1. The density of air is proportional to the number of particles of air occupying a particular space. 2. In the atmosphere, the relationship between temperature and pressure is not always fixed.
32 3. A temperature inversion is an increase in temperature with height in an atmospheric layer. 4. The amount of water vapor in air is referred to as humidity.
33 5. The ratio of water vapor in a volume of air relative to how much water vapor that volume of air is capable of holding is called relative humidity. 6. Relative humidity is expressed as a percentage.
35 III. Moisture in the atmosphere A. Cloud formation. 1. Clouds form when warm, moist air rises, expands and cools in a convection current. As the air reaches its dew point, the water vapor in the air condense around condensation nuclei.
37 2. Condensation nuclei are small particles in the atmosphere around which cloud droplets can form. 3. Clouds can also form when wind encounters a mountain and the air has no place to go but up. 4. This method of cloud formation is called orographic lifting.
49 5. When cloud droplets collide, they join together to form a large droplet in a process called coalescence. 6. As the process continues, the droplet becomes too heavy to be held. Gravity takes over and the droplet fall to earth- precipitation. Either liquid or a solid.
50 C. The water cycle 1. The process of water changing from liquid to gas is called evaporation. 2. The first step- water evaporates from lakes and streams. 3. As the water vapor rises, it cools and changes back into liquid.