The Climate of the Earth

The Climate of the EarthChapter 3Earth-Sun RelationshipChapter 3 Section 1Weather

Weather the condition of the atmosphere in one place during a limited period of timeEx: looking out the window to see if you need an umbrella means youre checking the weather

Climate

Climate term for the weather patterns that an area typically experiences over a long period of timeEx: not having to look out of the window because it is usually raining, so you take an umbrella anywayEarths Tilt & Rotation

The tilt is one reason for variations in sunlightAxis an imaginary line running from the North Pole to the South PoleThe angle of tilt never changes and because of it: not all places on the planet receive the same amount of direct sunlight at the same timeTemperature is greatly affected by the earths tiltThe measure how hot or cold a place isWarmer temperatures: areas that receive a lot of direct sunlightColder temperatures: areas that receive a less direct sunlightTemperatureRotation

Receiving light also depends on the side of planet that is facing the sunOne full rotation takes up to 24 hoursThis also causes the alteration between day and nightRevolution

While rotating on its axis, the earth is also traveling in an orbit around the sunA revolution is a trip around the sunIt takes the earth a few hours more than 365 days to complete one revolutionBoth the revolution & the tilt cause changes in the angle and amount of sunlight that reach different parts of the earthThese changes are called seasonsWe experience different amounts of day and night, as well as different temperatures during seasonal changesRevolution & TiltRevolution & Tilt

Seasons are reversed north and south of the EquatorSpring in the N. Hemisphere ~> fall in the S. HemisphereWinter in the S. Hemisphere ~> summer in the N. HemisphereTropic of Cancer

This is the northernmost point on the earth to receive the direct rays of the sunEventually the sun strikes directly on the line of latitude: 23 NorthTropic of Cancer

The rays reach the Tropic of Cancer on or about June 21It gives the N. Hemisphere its longest day of sunlightThis is also known as the summer solstice It marks the beginning of summer in the N. HemisphereTropic of Capricorn

Now the suns rays strike south of the equator reaching 23 SouthThis is the southernmost point where the suns direct rays reachTropic of Capricorn

The rays reach the Tropic of Capricorn on or about December 21st It gives the N. Hemisphere its shortest day of sunlightIt is also known as the winter solstice It marks the beginning of winter in the N. Hemisphere

6 months of the year, 1 pole is tilted toward the sun and receives continuous sunlightThe other pole is tilted away from the sun and receives little to no sunlightBetween March 20 September 23: the sun never sets at the North PoleIt is known as the midnight sunThe PolesLand of the Midnight Sun

On the sunniest days in the warmest climates still only a part of the suns radiation passes through the atmosphereSome is reflected back into spaceEnough reaches the earth to warm the air, land, and waterGreenhouse EffectGreenhouse Effect

Earth acts like a greenhouse because it traps some heat and keeps it from escaping back into space too quicklyIt traps the warmth for growing plants even in cold weatherThis is known as the greenhouse effectIf too much heat escapes, the plants will freezeIf too much heat is trapped, the plants will dry outGreenhouse EffectThe atmosphere provides just the right amount of insulation to promote life50% of the suns radiation that reaches the earth is converted into infrared radiation (heat)Cloud and greenhouse gases absorb the heat reflected by the earth and radiate it back so that a balance is createdGeneral Rules of G.E.CO2 within the atmosphere has risen rapidly because of human interaction with the environment:Burning of coalBurning of petroleumBurning of other fossil fuels Burning of the tropical rain forestsTodays SituationBecause of rising CO2 levels this has also increased a rise in global temperatures This is called global warming Some believe that if temperatures continue to rise, ice caps and mountain glaciers will melt and cause a rise in sea levelsErosion of cliffs, beaches, and dunes could also increasePlaces could become submergedGlobal WarmingGlobal Warming

Factors Affecting ClimateChapter 3 Section 2Low Latitudes are located between the Tropic of Cancer and the Tropic of CapricornIt includes the Equator and places here have warm to hot climatesLow LatitudesHigh Latitudes are located in the earths polar areasBetween March 20 September 23 the polar area north of the Arctic Circle experiences continuous daylight/twilightThe polar area south of the Antarctic Circle experiences continuous daylight/twilight for the other 6 months of the yearHigh LatitudesThe mid-latitudes are located: North between the Tropic of Cancer and the Artic Circle South between the Tropic of Capricorn and the Antarctic CircleIn the summer these areas receive warm masses of air from the TropicsIn the winter they receive cold masses of air from the high latitudesMid-LatitudesThe earths atmosphere becomes thinner as altitude increasesThinner air retains less heatAs elevation decreases, temperatures decreaseThis effect occurs at all latitudesElevation & ClimateWind

Wind & water combine with the sun to affect earths weather and climateWind is air that moves across the face of the earthIt occurs because the sun heats up the earths atmosphere and surface unevenly

Rising warm air creates areas of low pressureFalling cool air causes areas of high pressureCool air then flows in to replace the warm rising airThese movements over the earths surface cause windsWinds distribute the suns heat around the planetWhat causes wind?Prevailing Winds are global winds which blow in fairly, constant patterns Their direction is determined by latitude and is affected by the earths movementEarth rotates to the east, therefore global winds are displaced clockwise in the N. Hemisphere and counterclockwise in the S. HemisphereThis is called the Coriolis EffectWind PatternsEquator: global winds are diverted north and south which leaves a narrow, windless zone called the doldrumsHorse Latitudes got their name from sailors who would toss cargo from their ships in order to get their ships to sail Horse LatitudesCurrents are cold and warm streams of waterThey are caused by the earths rotation, changes in air pressure, and differences in water temperatureThe Coriolis Effect also takes place in the oceanCurrents move clockwise in the N.H. and counterclockwise in the S.H.Ocean CurrentsOcean currents affect climate in the coastal landsCold ocean currents cool the lands they passWarm ocean currents bring warmer temperaturesOcean CurrentsWind & water work together to affect weatherCondensation creates precipitationWater vapor forms in the atmosphere from evaporated surface waterColder temperatures cool the rising moist airThen the vapor condenses into liquid droplets to form cloudsWeather & the Water CycleThe surface of the earth can also be affected by climateLarge bodies of water are slower to heat and to cool than landWater temperatures are more uniform and constant than land temperature, this means their temperature changes slowlyLandforms & ClimateMountain ranges also influence precipitation and affect climateWinds that blow over an ocean are pushed upward when they meet a mountain rangeRising air cools and release most of its moisture in the form of precipitation It does this on the windward side the side of the mountain range facing the windLandforms & ClimateAfter precipitation is released, winds become warmer and drier when they come down on the opposite side of the mountain, or leeward sideHot, dry air produces little precipitation in an effect known as a rain shadowThis causes dry areas to develop on the leeward side of mountain rangesLandforms & ClimateWorld Climate PatternsChapter 3 Section 3Geographers divide the earth into climate regions:TropicalDryMid-LatitudeHigh LatitudeHighlands Each of the subdivisions has its own characteristic soils and natural vegetationThe plant life that grows in an area where the natural environment is unchanged by human activityClimate RegionsTropical Rain Forest

They are found in or near low latitudes the TropicsTropical rain forest and tropical savanna are the 2 most widespread kinds of climate regionsTropical rain forest climates have an average temperature of 80FYearly rainfall averages about 80 inchesTropical Climates

Lush vegetation is common and grows thickly in layersTeak or mahogany trees form a canopy over smaller treesOn the floor we have plants that grow under the shade The Amazon River Basin is the worlds largest tropical rain forestTropical Savanna

These areas have dry winters and wet summersThey also have high year-round temperaturesDuring the dry season the ground is covered with clumps of coarse grassThere are fewer trees than in the rain forestsThey can be found in Africa, Central & South America, and AustraliaThere are 2 types of dry climatesDesertSteppeDry ClimatesDeserts

These are areas with sparse plant lifeYearly rainfall very rarely exceeds 10 inchesTemperatures vary from the heat of the day to the cool of night & from season to seasonIn some desert areas, underground springs may support an oasisThis is an area of lush vegetationSome deserts have dunes or rocky surfaces and others have fertile soilDry ClimatesSteppes

They are dry, largely treeless grasslands and they border deserts Yearly rainfall averages 10 to 20 inchesThe largest steppe stretches eastern Europe and western and central AsiaThey are also found in North America, South America, Africa, and Australia They include 4 temperate climate regionsMarine west coastMediterraneanHumid subtropicalHumid continental They experience variable weather patterns and seasonal changesThey give rise to a variety of natural vegetationMid-Latitudes ClimatesMarine West Coast

Between the latitudes of 30 & 60 north and southEx: Pacific coast of N. America, much of Europe, parts of S. America, Africa, Australia and New Zealand Abundant rainfall supports the growth of both coniferous and deciduous treesConiferous

Coniferous trees such as evergreens have cones, needle-shaped leaves, and keep their foliage throughout the winterDeciduousDeciduous trees such as oak, elm, and maple, that have broad leaves that change color and drop in autumn

Mixed Forest

Mixed Forests have both kinds of trees and are typical of marine west coast climatesMediterranean

The Mediterranean climates are lands surrounding the Mediterranean SeaThey have mild, rainy winters, and hot, sunny summersThe natural vegetation includes chaparral which are thickets of woody bushes and short treesHumid Sub-Tropical

This is the area in the southeastern United States and in the southeastern parts of South America and AsiaThey experience short, mild winters and rain nearly year-roundVegetation consists of prairies (which are inland grasslands) as well as forests of evergreen and deciduous treesThese are regions of the Northern Hemisphere such as southern Canada, western Russia, and northeastern ChinaThe farther north a person travels the longer and more severe are the snowy winters and the shorter and coolers are the summersVegetation includes evergreens which outnumber deciduous trees Humid Continental Here, freezing temperatures are common much of the year because of the lack of direct sunlightVegetation is limited in quantity & varietyHere we have 2 regions:SubarcticTundra High LatitudeSubarcticWinters here are bitterly cold and summers are short and coolIn some parts only a thin layer of surface soil thaws each summerBelow it is permafrost permanently frozen subsoil

Tundra

They are closer to the polar regions and are very coldWinter darkness and bitter cold last for half the year and the suns indirect rays bring constant summer light but little heatThe layer of thawed soil is even thinner than in the subarcticVegetation is limited to short grasses, mosses, and lichens Highlands

The higher the elevation the cooler the temperaturesThe natural vegetation also varies with elevationMixed forests generally lie at the bases of mountainsHigher up, meadows with small trees, shrubs, and wildflowers are in the mountainsideScientists try to find answers for climatic changes by studying the interrelationships among ocean temperatures, greenhouse gases, wind patterns, and cloud coverClimate ChangesThe last 1 to 2 million years the earth passed through 4 ice agesOne hypothesis (education guess) is that the earth absorbed less solar energy because of changes in the suns output of energy or because of the earths change in orbitAnother hypothesis says that dust clouds from volcanic activity reflected sunlight back into space, cooling the atmosphere and lowering surface temperatures Ice AgesBurning of fossil fuels releases gases that mix with water in the air, forming acids that fall in rain and snow Acid rain can destroy forestsExhaust released from burning fossil fuels in engines and factories is heated in the atmosphere by the suns UV rays forming smogThis is a visible chemical haze in the atmosphere that endangers peoples healthHuman Interaction