Chapter 25.1Chapter 25.1““Factors that Affect Factors that Affect

ClimateClimate””

Modified from many sources & Holt CA Earth Scienceby L. Smith

Factors That Affect Factors That Affect ClimateClimate

CLIMATE = WEATHER

CLIMATE = The AVERAGE weather conditions over a LONG period of time

Factors That Affect Factors That Affect ClimateClimate CLIMATE = most often described by:

AVERAGE TEMPERATUREand

ANNUAL PRECIPITATION

I.I. LatitudeLatitude

II.II. Heat Absorption & ReleaseHeat Absorption & Release

III.III. TopographyTopography

Factors That Affect Factors That Affect ClimateClimate

I.I. LatitudeLatitude

• • The sunThe sun’’s rays strike the s rays strike the equatorialequatorial region at a much more region at a much more directdirect angle angle than the poles, making the average than the poles, making the average temperature at the temperature at the polespoles much much coldercolder and the average temperature at the and the average temperature at the equator much equator much warmerwarmer..

Factors That Affect Factors That Affect ClimateClimate

Latitude Latitude

• Solar energySolar energy striking the Earth striking the Earth’’s surface s surface near the near the polespoles is is lessless intense than radiation intense than radiation striking the Earth near the striking the Earth near the equatorequator..

http://www.geogrify.net/GEO1/Lectures/EnergyAtmosphere/SolarEnergy.html

Latitude Latitude

Latitude Latitude Global Wind Patterns

Differing amounts of solar energy, and the spinning of the Earth, create different wind patterns at different latitudes .

Latitude Latitude Global Wind Patterns

Wind patterns at different latitudes then influence precipitation patterns.

II.II. Heat Absorption & ReleaseHeat Absorption & Release

•• Different Different surfaces surfaces heat and cool at heat and cool at different different ratesrates creating creating windwind patterns patterns and and ocean ocean currentscurrents..

Factors That Affect Factors That Affect ClimateClimate

Heat Absorption & Heat Absorption & Release Release Land vs. Water

The differential heating and cooling of land and water creates winds.

Land heats AND cools faster than water.

Heat Absorption & Heat Absorption & Release Release Specific Heat & Evaporation

Specific heat is the amount of energy required to raise the temperature of a substance 1 degree C.

Heat Absorption & Heat Absorption & Release Release Specific Heat & Evaporation

Water requires a larger amount of energy to increase temperature than most substances.

Evaporation of water absorbs a lot of energy too (think sweat!).

Heat Absorption & Heat Absorption & Release Release Ocean Currents

Ocean currents can have a large influence on air masses over the landthey contact.

http://geology.uprm.edu/Morelock/2_image/ocncur.jpg

Heat Absorption & Heat Absorption & Release Release El NiñoEl Niño Southern Oscillation

• El Niño - the name given to the periodic warming of the ocean that occurs in the central and eastern Pacific.

• At irregular intervals of 3-7 years, these warm countercurrents become unusually strong and replace normally cold offshore waters with warm equatorial waters.

Heat Absorption & Heat Absorption & Release Release El NiñoEl Niño Southern Oscillation

• A major El Niño episode can cause extreme weather in many parts of the world.

Increase precipitation and landslide activity in southern California and the SouthwestDrought to the northern Rocky Mountains

Heat Absorption & Heat Absorption & Release Release Normal ConditionsNormal Conditions

Heat Absorption & Heat Absorption & Release Release NormalNormal Conditions

Normally, strong trade winds blow from the east along the equator, pushing warm water into the Pacific Ocean.

Heat Absorption & Heat Absorption & Release Release El NiñoEl Niño Conditions

Heat Absorption & Heat Absorption & Release Release El NiñoEl Niño Conditions

An El Niñño condition results from weakened trade winds in the western Pacific Ocean near Indonesia, allowing piled-up warm water to flow toward South America.

Heat Absorption & Heat Absorption & Release Release La NiñaLa Niña

• Researchers have come to recognize that when surface temperatures in the eastern

Pacific are colder than average, a La Niñña event is triggered that has a distinctive set of weather patterns.Droughts in parts of the South and Southwest from Arizona to Arkansas and LouisianaAbove normal precipitation in the Northwest and the Tennessee Valley area

Heat Absorption & Heat Absorption & Release Release Seasonal Winds

Monsoons Monsoons are the are the seasonal reversal seasonal reversal of wind direction of wind direction associated with associated with large continents, large continents, especially Asia especially Asia (which affects the (which affects the Indian sub-Indian sub-continent). continent).

http://www.mrdowling.com/images/612monsoons.png

Heat Absorption & Heat Absorption & Release Release Monsoons

• In summer, the In summer, the wind blows wind blows from sea to from sea to land.(wet)land.(wet)

• In winter, the In winter, the wind blows wind blows from land to from land to sea.(dry)sea.(dry)

http://volney-bodley-weather-project.wikispaces.com/file/view/monsoon.gif/219925242/monsoon.gif

Monsoon Photos

More about monsoons--click here

III.III. TopographyTopography• • Topographic features such as Topographic features such as

mountainsmountains play an important role in play an important role in the amount of the amount of precipitationprecipitation that falls that falls over an area.over an area.

Factors That Affect Factors That Affect ClimateClimate

Topography Topography Elevation

Elevation is height above sea level

Temperature generally decreases as elevation increases.

As humid air on the As humid air on the windwardwindward side of the side of the mountain moves up the slopes it mountain moves up the slopes it coolscools, , condensescondenses, and forms , and forms cloudsclouds and rain. and rain.

By the time the air reaches the By the time the air reaches the leewardleeward side of side of the mountain, most of the moisture is the mountain, most of the moisture is lostlost..

The Rain Shadow EffectThe Rain Shadow Effect

The Rain Shadow EffectThe Rain Shadow Effect

TheThe dry dry area on area on the the leewardleeward side side of the mountain of the mountain is called a is called a rain rain shadowshadow..

RAIN RAIN SHADOWSHADOW

http://classconnection.s3.amazonaws.com/436/flashcards/774436/jpg/picture11320597452956.jpg

The Rain Shadow EffectThe Rain Shadow Effect

http://www.geography.hunter.cuny.edu/~tbw/wc.notes/15.climates.veg/climate/B ...

The Rain Shadow EffectThe Rain Shadow Effect

The dry area on The dry area on the leeward side the leeward side of the mountain of the mountain is called a is called a rain rain shadowshadow..

http://www.sierranevadaphotos.com/geography/sierra_precipitation.asp

Climate Data for Two Climate Data for Two CitiesCitiesThis climate graph shows This climate graph shows

data for two cities, both data for two cities, both located in Arizona. located in Arizona. Phoenix has an elevation Phoenix has an elevation of of 338 m338 m and Flagstaff has and Flagstaff has an elevation of an elevation of 2134 m.2134 m.

• How does the elevation How does the elevation affect the annual affect the annual temperature and temperature and precipitation?precipitation?

• What causes this What causes this difference to occur?difference to occur?

IV. IV. Bodies of WaterBodies of Water• • LargeLarge bodies of bodies of waterwater, ,

such as lakes and such as lakes and oceans, alter the oceans, alter the climateclimate of an area.of an area.

• Places Places downwind downwind of a of a large body of water large body of water generally have generally have cooler cooler summerssummers and and milder milder winterswinters than places of than places of the same latitude that are the same latitude that are further further inlandinland..

Other Factors That Affect Other Factors That Affect ClimateClimate

IV. IV. Bodies of WaterBodies of Water

Other Factors That Affect Other Factors That Affect ClimateClimate

•• CoastalCoastal areas (or areas near large areas (or areas near large lakes like the Great Lakes) lakes like the Great Lakes)

generally have generally have moremore precipitation precipitation than than inlandinland areas. areas.

http://quizlet.com/15961300/print/

V. V. Atmospheric CirculationAtmospheric Circulation

• • Global winds Global winds are are another factor that another factor that influences climate influences climate because they because they distribute distribute heatheat and and moisturemoisture around around Earth.Earth.

Other Factors That Affect Other Factors That Affect ClimateClimate

http://www.fas.org/irp/imint/docs/rst/Sect14/09globalcirccomp.jpg

V. V. Atmospheric CirculationAtmospheric Circulation•• LowLow-pressure zones -pressure zones

at the at the equator equator and in and in the the sub-polar sub-polar regions form regions form clouds clouds that drop much more that drop much more annual annual precipitation precipitation in the form or rain or in the form or rain or snow depending on snow depending on the average the average temperaturestemperatures of the of the area.area.

Other Factors That Affect Other Factors That Affect ClimateClimate

http://www.weatherwizkids.com/globalcirculation.gif

V. V. Atmospheric CirculationAtmospheric Circulation

Notice the cloud cover over the equator Notice the cloud cover over the equator (equatorial low) and clear skies over the tropics (equatorial low) and clear skies over the tropics

(subtropical highs.)(subtropical highs.)

Other Factors That Affect Other Factors That Affect ClimateClimate

VI. VI. VegetationVegetation

• • Vegetation can Vegetation can affect both affect both temperature temperature and and precipitationprecipitation patterns in an area patterns in an area by influencing how by influencing how much of the Sunmuch of the Sun’’s s energyenergy is absorbed is absorbed and how quickly this and how quickly this energy is energy is releasedreleased..

Other Factors That Affect Other Factors That Affect ClimateClimate

VI. VI. VegetationVegetation • Plants release Plants release water water vapor vapor through their through their leaves into the air via leaves into the air via transpirationtranspiration..

• Vegetation also Vegetation also releases releases particlesparticles that that act as cloud act as cloud seedsseeds and increase and increase precipitationprecipitation..

Other Factors That Affect Other Factors That Affect ClimateClimate

http://vjh.flbsd.mb.ca/wp-content/uploads/2012/08/transpiration.jpeg