Global Patterns of Atmospheric Movement

Global Patterns = of Atmospheric Movement

Temperature Differences: Land-Water-Atmosphere

The Atmosphere:

Weather is the condition of Earth’s atmosphere at a particular time and place. The atmosphere is a thin layer of gases that surrounds the Earth and forma a protective covering around the planet. In addition to gases, the atmosphere contains small solid particles such as du= st, salt, pollen. There are also = small liquid droplets other than water in clouds. The Earth’s atmosphere is ma= de up of nitrogen, oxygen, carbon dioxide, water vapor, and other gases along with particles of liquids and solids. The atmosphere makes conditions on Earth possible for living things.=

Excel Project:<= /p>

Use the data table b= elow to create a pie graph, a bar graph, and a line graph in an Excel Spreadsheet. = Technology Standards: Performance Indicators 1.22 and 1.24.



G= ases in the Atmosphere

P= ercents

Nitrogen

78%

Oxygen<= /span>

21%

Other gases

1%

Properties of Air:=

Air is matter and has mass. It also has density and pressure properties. Density is the amount of mass in a given volume and can be calculated with the following equation.<= /span>

Density =3D Mass / Volume

Pressure is a force pushing on an area or surface.&= nbsp; Denser air exerts more pressure than less dense air. The instrument that is used to mea= sure air pressure is a barometer. (mercury barometers and aneroid barometers). Remember: air pressure decreases as altitude increases. When the air press= ure decreases, the density also decreases.

Layers of the Atmosphere:=

The atmosphere consists of four main layers and they are classified according to changes in the atmosphere. The four main layers of the atmosp= here are the troposphere, stratosphere, mesosphere, and thermosphere.=

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The laye= r of atmosphere nearest the Earth’s surface is called the troposphere. Conv= ection drives to turn over the air. = Here is found 80% of the total mass of the atmosphere and most of the water vapo= r in the atmosphere.

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The dry = clear layer of atmosphere above the troposphere is called the stratosphere. Thi= s is the layer of atmosphere where molecules of ozone can be found. Ozone in the stratosphere protects= Earth from a type of solar radiation harmful to living things by absorbing the radiation. This radiation inc= reases temperature in this atmosphere level and the temperature of the air increas= es as you rise higher in this layer.

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You now = enter the mesosphere which is very t= hin and has less than .1% of the atmosphere’s mass. Meteors entering the mesosphere bu= rn up in this level most of the time. This layer is heated from below and decreases in temperature as you rise higher. The outer mesosphere is the coldes= t part of the atmosphere with temperatures around -90^oC.

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The thermosphere is heated with radia= tion from the sun which makes the temperature of this layer rise as you move upward. This layer becomes le= ss dense until it becomes outer space. This layer is divided into two layers called the lower ionosphere an= d the upper exosphere. In the ionosphere, energy from the sun c= auses the molecules to become electrically charged. These charged particles are called ions. The aurora borealis occurs here when particles from the sun enter t= his layer near the North Pole and the particles hit oxygen and nitrogen atoms.<= span style=3D'mso-spacerun:yes'> The result is a glow. The exosphere is the outer layer of the thermosphere. Satellites orbit in the exosphere = aiding satellite TV, cell phones, weather watching, and telescopes looking into de= ep space.

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Energy and the Atmosphere:

Energy f= rom the sun reaches Earth as visible light and infrared radiation. There = is also a small amount of ultraviolet radiation. As the Earth’s surface is he= ated, it radiates some of that energy it absorbs back into the atmosphere towards space as infrared radiation. You can not see it, but you can feel radiation. The direct transfe= r of heat from one substance to another substance that touches is conduction. As air moves over warm land or air= , the molecules in the air are heated by direct contact. The transfer of heat by the moveme= nt of a fluid is called convection.<= span style=3D'mso-spacerun:yes'> Convection circulates heat through= the atmosphere. Convection is responsible for most of the heating of the troposphere. The upward movement of warm air an= d the downward movement of cool air form convection currents in the troposphere.<= o:p>

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Global Winds:

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Global winds are produced by the movement of air between the equator and the poles. <= /span>Because the Earth rotates from west to east, the winds seem curved. This curving of the winds is known= as the Coriolis effect. Global winds turn to the right in = the northern hemisphere and left in the southern hemisphere. Northern hemisphere winds are nort= heast and south winds will change to southwest winds. In the Southern hemisphere a south= wind blows southeast and a north wind becomes a north west wind.

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The main= global winds are the trade winds, the= prevailing westerlies, and the polar easterlies. There are also calm areas of falli= ng air called the horse latitudes. A calm area where warm air rises is called the doldrums.

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The wind= s near the equator are weak with little or no wind where warm air is rising is cal= led the doldrums. The horse latitudes are another area of little or no wind where the= air is falling. The horse latitud= es are found at 30^onorth and south latitudes. The trade winds blow from the horse latitudes toward the equator. These winds blow from the northeas= t in the northern hemisphere and southeast in the southern hemisphere. These winds carried cargo from Eur= ope to the West Indies and South American regul= arly in the 1800’s. The prevailing westerlies blow from t= he west to the east. In the nort= hern hemisphere the prevailing westerlies blow from the southwest and in the southern hemisphere the prevailing westerlies blow from the northwest. The polar easterlies meet the prevailing westerlies. The polar easterlies blow away fro= m the poles. The polar easterlies a= t the North Pole blow from the northeast and the polar easterlies at the South Po= le blow from the southeast. Ther= e are also high speed winds traveling from west to east in wave like patterns and= are called jet streams.=

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Water and the Atmosphere:

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Water vapor enters the atmosphere from the pro= cess of evaporation when water molecules from liquid water escape into the atmosphere from the surface of the liquid body. Living things add water vapor to t= he atmosphere. When people exhal= e, water vapor is added to the environment.&n= bsp; Water vapor is also loss from plant leaves as water molecules are released from the leaves. Som= e of this water vapor condenses and forms clouds. Humidity is a measure the amount of water vapor in the air. The dew point is the temperature at w= hich condensation begins.

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Clouds a= re classified into three main types of clouds are cumulus, stratus, and cirrus. They are also classif= ied using their altitude. Cumulus clouds are fluffy like co= tton and are mostly a sign of fair weather.&nbs= p; Stratus clouds form fla= t like layers are cover lots of the sky. As they thicken and turn dark, they are called nimbostratus and may produce precipitation. Cirrus clouds are feathery and fo= rm at high altitudes over 6 kilometers. They contain mostly ice crystals.&n= bsp; Precipitation includes = rain, sleet, freezing rain, hail, and snow.

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Wind Systems: fronts and air masses:<= /span>

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Air Masses

Temperat= ure and humidity are used to classify air masses.&= nbsp; Warm air masses form in the tropics. Cold air masses form north of 50o north latitude or form south of 50^o south latitude. Tropical warm air masses have low = air pressure and polar cold air masses have high air pressure. Air masses that form over water ar= e called maritime air masses and air ma= sses that form over land are called con= tinental air masses. Maritime air = masses can become very humid, and continental air masses are generally dry when th= ey form in the middle of the continents. The weather in North America is influenced by four major air masses:

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Maritime tropical air masses coming from the Gulf of= Mexico bring warm, humid air to the eastern United States.

Maritime tropical air masses coming from the Pacific = Ocean bring warm humid air into Cal= ifornia and much of the Southwest.

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Maritime polar air masses coming from the Atlantic Ocean are many times pushed out to sea by westerly winds.

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Maritime polar air masses coming from the Pacific Ocean bring cool humid air to the West Coas= t.

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Continental tropical air masses coming from the Southwest bring hot, dry air.

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Continental polar air masses coming from central and northern Canada bring = cold air into the central and eastern United States.

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Fronts

A front is where air masses meet an= d do not mix. The four types of fr= onts are cold fronts, warm fronts, stat= ionary fronts, and occluded fronts.

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·        When warm are moves over cold air, it is called a warm front.

·        When cold air moves under warm air, it is called a cold front and the warm air is forced upward.=

·        When warm air and cold air meet and do not have enough force for one to move the other, it is called a stationary f= ront that stalls over an area.

·        When cold air meets cool air trapping warm air in the middle, the warm air moves upward and this is called an occlu= ded front.

Sea Breezes and Land Breezes:

Convection currents occur where land and ocean meet. A sea breeze occurs during the day. During the day the sun warms the land more than the water. The air over the land is heated fr= om conduction. The warm air over= the land is less dense with low pressure so it rises. The cool air over the water is mor= e dense with high pressure. The coole= r air over the water flows toward the land and a convection current begins with winds blowing from the water toward t= he land. <= /p>
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Convection currents occur where land and ocean meet. A land breeze occurs at night. A= t night, the land cools faster than the water. Air over the land becomes cooler than the air over the water. The air over the land that is cool= er with higher pressure and denser moves towards the warmer air over the water. The air over the water= that is warmer with low pressure and density rises and moves toward the cooler a= ir over the land and a convection current begins with winds blowing from the land toward the water.=

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Weather Forecasting:

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A line t= hat connects points of equal atmospheric pressure is called an isobar. Isobars t= hat are close together indicate a great difference is pressure over a small area. This will result in str= ong winds. Isobars that are sprea= d out indicate a small difference in pressure.&n= bsp; This will result in gentle winds.&n= bsp; Isobars show the high and low pressure locations.

Lines th= at connect locations of equal temperature are called isotherms.

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        =             &nb= sp;          Isobars connect=

            =             &nb= sp;      equal pressure

     Isotherms connect

  &n= bsp; equal temperature

Climate Changes:

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The clim= ate has been changing throughout Earth’s history. Gradually over millions of years t= here have been warm periods and cold periods.&n= bsp; The cold periods are called ice ages. Glaciers form durin= g ice ages and are huge sheets of ice that form and cover large parts of the Earth’s surface. The movement of the continents has ta= ken millions of years. 225 million years ago, there was one continent called Pangaea. The continents broke away over mil= lions of years and have over time gradually moved to their present positions. This has changed the locations of = land and sea and this changed global patterns resulting changing climates. The continents continue to move an= d so climate will continue to change also.

G= ases in the Atmosphere	P= ercents
Nitrogen	78%
Oxygen<= /span>	21%
Other gases	1%