Meteorology Earth’s Atmosphere Weather and Climate

Atmosphere Layer of gases that surrounds the Earth Composed of 78% nitrogen, 21% oxygen, and 1% of CO 2, H 2 O vapor, Ne, He, Kr, Xe, methane, H 2 and ozone

Cycles Oxygen-Carbon dioxide cycle Plants use carbon dioxide for photosynthesis to make glucose, which releases oxygen. Animals use oxygen for respiration to break down glucose, which releases carbon dioxide.

Oxygen-Carbon dioxide cycle

Cycles Nitrogen cycle Bacteria in soil convert N 2 in the air into N 2 in soil. Plants use N 2 and release it into air. Animals leave waste products containing N 2, which goes into the soil. Plants use N 2 and release it into the air.

Nitrogen Cycle

Layers of the Atmosphere Troposphere – bottom layer of the atmosphere, extending from the ground level up to about 16 kilometers above the Earth; area in which life and weather is located Stratosphere – second layer of the atmosphere; includes the ozone layer –Ozone layer: a layer of O 3 which reduces the energy of ultraviolet radiation, making it safer

Layers of the Atmosphere Mesosphere – third layer of the atmosphere; the coldest layer Thermosphere – outermost layer of the atmosphere; temperatures increase because N 2 and O 2 absorb Sun’s energy –Ionosphere: layer of the thermosphere containing ions, or electrically charged, particles

Clouds Sun’s heat causes liquid water on the surface to evaporate, changes from a liquid to a gas. The gas, water vapor, becomes part of the air and rises. As water vapor rises, it cools and condenses, changes from gas to a liquid. As water vapor condenses, it collects to form clouds

Types of Clouds Stratus cloud – low, flat cloud that forms in layers –Fog: stratus cloud that forms near the ground Cumulus cloud – puffy, white cloud occurring at medium altitudes Cirrus clouds – high, wispy clouds made of ice crystals.

Cumulus Stratus Cirrus

Precipitation Moisture that falls to the Earth from the atmosphere As clouds collect more condensing water vapor, gravity begins to cause the droplets to fall. If the air temperature is above freezing, the droplets fall as rain. If the air temperature is below freezing, the droplets fall as snow.

Wind Patterns Wind cell – continuous cycle of rising warm air and falling cold air As air nears the equator, the Sun heats the air, making it less dense. Therefore, it rises. As warm air rises, it cools as it reaches the upper part of troposphere, making it more dense. Therefore, it falls.

Wind Belts Rotation of the Earth breaks up the wind cells into small cells Wind belt – pattern of wind movement around the Earth Trade wind – strong, reliable wind just north or south of the equator; blows from the east Prevailing westerly – wind generally between 30° N and 60° N latitudes; blows from the west Polar easterly – wind near the poles; blows from the east

Wind Belts

Weather Conditions and Measurement Weather – state of the atmosphere at a given time and place Air temperature – a measure of the movement of air particles –Measure with a thermometer in degrees (°) Air pressure – force of air against a unit of area –Measured with a barometer in centimeters (cm) Humidity – amount of water vapor in the air –Measured in percentage (%) Relative humidity – amount of water vapor in the air compared to the maximum amount of water vapor the air can hold

Weather Conditions and Measurement Anemometer – instrument used to measure wind speed Wind vane – instrument used to find wind direction Rain gauge – instrument used to measure the amount of rainfall

Weather Patterns and Predictions Air mass – large section of the atmosphere with the same temperature and humidity throughout Front – moving boundary line between two air masses Warm front – boundary ahead of a warm air mass that is pushing out and riding over a cold air mass Cold front – boundary ahead of a cold air mass that is pushing out and wedging under a warm air mass.

High pressure – cold area of high air pressure Low pressure – warm area of low air pressure Isobar – line on a weather map connecting areas of equal air pressure Weather Patterns and Predictions

Storms Thunderstorms – occurs when warm air is forced upward by a cold front Large, dark cumulus clouds produce lightning, thunder and sometimes heavy rain. High winds can also occur before and during the storm. As clouds pass over the ground, electrical charges build. When a current passes through the charges, we see lightning. Lightning expands the air rapidly, causing thunder

Storms Tornado – powerful wind storm with a whirling, funnel-shaped cloud and extremely low pressure Forms in open, level areas Warm, humid air becomes trapped by cool, dry air. Rotation occurs when warm air rushes up to meet cool air. Rotation “touches down” and a tornado forms

Storms Hurricane – severe tropical storm with high winds that revolve around an eye Form over the ocean near the equator Low pressure system causes winds to spin around at high speeds Produce tremendous rainfall amounts and high winds Usually slow as they proceed over land because they loose their moisture and friction with land slows the winds.

Climates Climate – average weather of a region over a long period of time Tropical zones – located between 0° and 30°N and 30° S, which have warm temperatures and high amounts of rainfall Temperate zones – located between 30° and 60°, which have cold winters and warm summers Polar zones – located between 60° and 90°, which have low temperatures and low precipitation

Factors that Affect Climate Angle at which sunlight hits the Earth –More direct, more heat; less direct, less heat Altitude above sea level –Higher elevation produces colder temperatures Nearness to large bodies of water –Close to an ocean, temperatures are mild; farther away from an ocean, temperatures are more extreme