Weather 1.notebook March 10, 2015

Transcription

1 Weather The Atmosphere and Weather: Insolation: is the solar energy that reaches a planet. It does not warm all places on Earth equally. The reason why it doesn't is because of the Earth's shape. The Earth's surface is curved, the same beam will strike Earth at a wider angle above or below the equator. Areas that are farther north or south of the equator receive less heat energy from the sunlight than areas closer to the equator. 1

2 Layers of the atmosphere: There are five layers of the atmosphere. The layer closest to the Earth's surface is called the troposphere. It is made up of gases. This layer is 5 11 miles thick. All weather occurs in this layer. The other layers are: stratosphere, mesosphere, thermosphere, and exosphere. Weather: Weather is a condition in the troposphere at a particular time and place. Factors that affect weather include temperature, wind,and cloud cover. Insolation: is the main source of energy on planet that we get from the sun. The amount of energy will vary. It will depend on the angle of sunlight, the length of daylight, and the location. 2

3 Air Pressure: It is all around us. It is the force exerted on you by weight of tiny particles of air. You don't feel this weight because atmospheric pressure pushes in all directions and these pushes balance each other. Air contains a mixture of gases, such as nitrogen and oxygen. Many variables affect air pressure. These include volume, temperature, height above the Earth's surface and the amount of water vapor. 3

4 Volume: is a measure of how much space an object takes up. Temperature: when air is heated, the gas particles speed up and spread out into larger space. Height Above Earth's Surface: Atmospheric pressure decreases with higher altitude. Altitude is the height above Earth's surface. Amount of Water Vapor: water vapor weighs less than most of the other gases in air. When water vapor is added to the air, the mixture of gases become lighter, and it exerts less pressure. Humidity: is the amount of water vapor in the air. 4

5 Global Winds: Global Winds: blow steadily over long distances in a predictable direction. They blow because sunlight heats areas near Earth's equator more than it heats areas near Earth's poles. The global winds are: polar easterlies, prevailing westerlies, trade winds. These winds will curve. The Coriolis Effect causes these winds to curve. Local winds: Sea breeze: it happens during the day. It is when wind blows from the ocean to the land. Land breeze: it happens during the night. It is when wind blows from the land to the ocean. Valley breeze: it happens during the morning. Cool air moves up out of the valleys to replace the rising warm air. Mountain breeze: it happens during the evening. As warm air rises over the valley, cool air from the mountains flows down into the valley. Measure air pressure and wind: barometer: measures the pressure of air. anemometer: measures wind speed using cups that rotate when the winds blow. Weather vane: is an instrument that shows which way the wind is blowing. Types of clouds and how they form: Cirrus clouds: form at the highest altitude. They usually form from ice crystals when liquid water is cooled below its freezing point. These clouds are wispy with fuzzy edges. Cumulus clouds: form from water droplets. They are puffy clouds. Stratus clouds: form from water droplets. They are layered clouds. They look blanketlike. Fog: is a cloud that forms near the ground. Air masses and fronts: Air mass: is a large region of air that has a similar temperature and humidity. Air masses can be cold or warm. An air mass that forms over a cold area will be cold and dry. An air mass that forms over a warm area will be warm and humid. Front: One air mass meets a different air mass, this meeting place between air masses is called a front. A front marks the front edge of the oncoming air mass. When a cold and dry air mass runs into a warm and moist air mass, the dense, heavy cold air pushes up lighter, warm air. This may cause a storm. When the temperature and humidity of the air masses behind a front are similar. The air masses don't move it will cause a stationery front. A stationery front is a boundary between two different air masses where neither one is strong enough to replace the other. Low pressure and high pressure system: Low pressure system: is a large air mass with low air pressure in the center. Since warm, humid air has low pressure it will usually bring warm and stormy weather. High pressure system: is a large air mass with the highest air pressure in the center. Since cool, dry air has high pressure it will usually bring dry, clear weather. Weather Maps: It shows the weather in a specific area at a specific time. It can show one variable an example would be air pressure, or many variables. On a weather map, symbols represent different variables. For example, cold fronts are shown by a blue line with blue triangles. The triangles point in the direction the front is moving. Warm fronts are marked with a red line of half circles that point in the direction the front is moving. Severe Storms: Thunderstorms: is a rainstorm that includes lightning and thunder. For a thunderstorm to happen warm air must rise, carrying moisture with it. An updraft( any upward movement of air) in a thunderstorm cause a cloud to increase in height, forming a tall cloud called a thunderhead. As rain falls, a downdraft may occur. A downdraft is a sudden downward movement of cool or cold air. Lightning: is the spark from the discharge of electricity that has built up in a thunderhead. Lightning can jump between parts of the same cloud, between different clouds, or between a cloud and the ground. Lightning raises the temperature of the air around it. This burst of heat makes the air expand violently. Thunder is the sound of the rapidly expanding air. 5

6 Winter Storms: They occur when two air masses of different temperatures and moisture levels meets. Blizzard: is a snowstorm with 35mph winds and enough snowfall that you can only see up to one quarter of a mile. Ice storm: is when a warm front approaches a cold air mass, the warm air mass usually pushes away the cold air mass. If rain falls as the warm air mass cools, the rain will freeze as it hits the cold air near the ground. An ice storm is a storm in which freezing rain forms a layer of ice on outside surfaces. 6

7 Tornadoes: A thunderstorm can turn into a tornado. A tornado is a rotating, funnel shaped cloud with wind speeds up to 300 mph. Another name for a tornado is a twister. Tornadoes begin forming when warm air moves upward in a thunderhead, creating low pressure area, it rotates faster and faster. The shape of the cloud looks like a funnel. The funnel occurs because warm air is rising up from the center of the cloud. 7

8 Hurricanes: Thunderstorms can also turn into a hurricane. Hurricanes start out as a tropical storms near the equator. A tropical storm has rotating winds with low pressure at its center. A tropical storm turns into a hurricane when wind speeds reaches more than 74 mph. The hole in the center of the hurricane is called the eye. A hurricane's fastest winds and heaviest rains occur next to the eye. 8

9 The area of the eye is calm, with no precipitation or wind. Hurricane winds whip up large waves in the ocean. These waves cause a bulge of water in the ocean known as a storm surge. This surge will cause water levels to suddenly rise. Any storm with a low pressure center that causes a circular pattern of winds to form is called a cyclone. 9

10 Climate: Climate: is the average weather of a place. Important variables in determining climate: Average temperature Average rainfall Another way to categorize an area's climate is to describe the plants that grow there. Distance from the water Ocean currents Mountain Ranges Winds Altitude 10

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