ClimateClimate

P. LoboscoP. Lobosco

Chapter 17-1Chapter 17-1What is climate?What is climate?

Objectives:Objectives: To describe what determines climate.To describe what determines climate. To explain how latitude, oceans and other To explain how latitude, oceans and other

factors affect the climate of a region.factors affect the climate of a region.

What Causes Climate?What Causes Climate?

Climate is the name for the general conditions Climate is the name for the general conditions of temperature and precipitation for an area of temperature and precipitation for an area over a long period of time. over a long period of time.

It determines the types of plants or animals It determines the types of plants or animals that can survive and it influences how people that can survive and it influences how people live.live.

Factors that Affect ClimateFactors that Affect Climate

LatitudeLatitude Large Bodies of WaterLarge Bodies of Water Ocean CurrentsOcean Currents MountainsMountains Rain ShadowsRain Shadows CitiesCities

LatitudeLatitude

Latitude is the measure of the distance north Latitude is the measure of the distance north and south of the equator. Latitude is measured and south of the equator. Latitude is measured in degrees. Areas close to the equator, or 0 in degrees. Areas close to the equator, or 0 degrees latitude, receive the direct rays of the degrees latitude, receive the direct rays of the sun. These direct rays provide the most sun. These direct rays provide the most radiant energy. Areas near the equator have a radiant energy. Areas near the equator have a warm climate. Polar regions have a cold warm climate. Polar regions have a cold climate.climate.

Latitude ZonesLatitude Zones

The tropics extend from the The tropics extend from the equator to 23.5º north and equator to 23.5º north and south. They receive the south. They receive the most direct solar radiation.most direct solar radiation.

The temperate zones extend The temperate zones extend from 23.5º to 66.5. These from 23.5º to 66.5. These areas receive moderate areas receive moderate amounts of solar radiation.amounts of solar radiation.

The polar zones from 66.5 º The polar zones from 66.5 º to the Poles receive very to the Poles receive very little solar radiation.little solar radiation.

Tropical ZonesTropical Zones

The tropical zones, which extend from 23.5º The tropical zones, which extend from 23.5º north and south latitude to the equator, have north and south latitude to the equator, have high temperatures and high humidity. high temperatures and high humidity. Tropical zones are also known as low-latitude Tropical zones are also known as low-latitude climates. The average temperature during the climates. The average temperature during the coldest month of the year does not fall below coldest month of the year does not fall below 18 degrees C. Many deserts are located on the 18 degrees C. Many deserts are located on the western coasts of the continents. This is western coasts of the continents. This is because the prevailing winds, the trades, blow because the prevailing winds, the trades, blow from east to west. from east to west.

Temperate ZonesTemperate Zones

In each hemisphere, the temperate zone is In each hemisphere, the temperate zone is found between 66.5ºand 23.5º latitude. In the found between 66.5ºand 23.5º latitude. In the areas of the temperate zones farther from the areas of the temperate zones farther from the equator, snow is common in the winter. equator, snow is common in the winter.

In the areas of the temperate zones closer to In the areas of the temperate zones closer to the equator, rain normally falls all year round. the equator, rain normally falls all year round. The average amount of precipitation is about The average amount of precipitation is about the same throughout. The average the same throughout. The average temperatures range from 5 º C to 20 ºC. temperatures range from 5 º C to 20 ºC.

Deserts in the Temperate ZoneDeserts in the Temperate Zone

Deserts in the temperate zones are usually Deserts in the temperate zones are usually located in land, far away from the oceans. The located in land, far away from the oceans. The winds that blow across these inland deserts winds that blow across these inland deserts carry little moisture. carry little moisture.

Although very hot during the day, Although very hot during the day, temperatures at night can drop to below temperatures at night can drop to below freezing. Inland deserts are found in Australia freezing. Inland deserts are found in Australia (the Great Sandy Desert) and Central Asia (the Great Sandy Desert) and Central Asia ( the Gobi Desert).( the Gobi Desert).

Polar ZonesPolar Zones

In each hemisphere, the polar zone extends In each hemisphere, the polar zone extends from the pole to about 60 degrees latitude. In from the pole to about 60 degrees latitude. In polar zones, the average yearly temperature is polar zones, the average yearly temperature is below freezing. There are some areas in the below freezing. There are some areas in the polar zones, such as the northern coasts of polar zones, such as the northern coasts of Canada and Alaska and the southern tip of Canada and Alaska and the southern tip of South America, where the snow melts during South America, where the snow melts during the warmest part of the year.the warmest part of the year.

Large Bodies of WaterLarge Bodies of Water

The surface temperature The surface temperature of water affects the of water affects the temperature of the water temperature of the water above it. Warm water above it. Warm water warms the air and cold warms the air and cold water tends to cool it.water tends to cool it.

Marine and Continental ClimatesMarine and Continental Climates

Within each of the three major climate zones, there Within each of the three major climate zones, there are marine and continental climates. Areas near an are marine and continental climates. Areas near an ocean or other large body of water have a marine ocean or other large body of water have a marine climate. Areas located within a large landmass have climate. Areas located within a large landmass have a continental climate. a continental climate.

Areas with a marine climate receive more Areas with a marine climate receive more precipitation and have more moderate temperatures. precipitation and have more moderate temperatures. A continental climate has less precipitation and a A continental climate has less precipitation and a greater range in temperature.greater range in temperature.

Ocean CurrentsOcean Currents Land areas near warm ocean Land areas near warm ocean

currents have warm currents have warm temperatures. temperatures.

The Gulf Stream is an ocean The Gulf Stream is an ocean current that carries warm current that carries warm water along the eastern water along the eastern coast of the United States.coast of the United States.

The California Current The California Current travels toward the equator travels toward the equator carrying cold water along carrying cold water along the west coast of the United the west coast of the United States.States.

ElevationElevation

Elevation, or altitude, is the distance above sea Elevation, or altitude, is the distance above sea level. As elevation increases, the air becomes level. As elevation increases, the air becomes less dense. This means there are fewer gas less dense. This means there are fewer gas molecules in the air and they are spread far molecules in the air and they are spread far apart. Less- dense air cannot hold as much apart. Less- dense air cannot hold as much heat as denser air. So as elevation increases, heat as denser air. So as elevation increases, temperature decreases.temperature decreases.

Rain ShadowsRain Shadows

Mountains also affect Mountains also affect regional climates.regional climates.

On the windward side of a On the windward side of a mountain range air rises and mountain range air rises and cold, and drops its moisture.cold, and drops its moisture.

On the leeward side the dry On the leeward side the dry air descends and dries the air descends and dries the land.land.

Deserts are common on the Deserts are common on the leeward side of the leeward side of the mountain ranges.mountain ranges.

CitiesCities

Large cities affect local Large cities affect local climate. climate.

Streets, parking lots and Streets, parking lots and building heat up and in turn, building heat up and in turn, heat the air. heat the air.

Air pollution heats up traps Air pollution heats up traps the heat, creating the heat-the heat, creating the heat-island effect.island effect.

Temperatures are at least 5º Temperatures are at least 5º higher than the surrounding higher than the surrounding areas.areas.

Chapter 17-2Chapter 17-2Climate TypesClimate Types

Objectives:Objectives: To describe a climate classification system.To describe a climate classification system. To explain how organisms adapt to a particular To explain how organisms adapt to a particular

climate.climate.

Koppen ClassificationKoppen Classification

Koppen classified world climates by using the Koppen classified world climates by using the annual and monthly averages of temperature annual and monthly averages of temperature and precipitation.and precipitation.

He then related the types and distribution of He then related the types and distribution of native vegetation to the various climates. native vegetation to the various climates.

It separates into six groups, tropical, mild, dry, It separates into six groups, tropical, mild, dry, continental, polar and high elevation.continental, polar and high elevation.

Classifying ClimateClassifying Climate

AdaptationsAdaptations

The climate determines the vegetation in the The climate determines the vegetation in the area. area.

Organisms adapt to their environment.Organisms adapt to their environment. An adaptation is any structure or behavior that An adaptation is any structure or behavior that

helps an organism survive its environment. helps an organism survive its environment. Structural adaptations are inherited and Structural adaptations are inherited and

develop in a population over a long period of develop in a population over a long period of time.time.

Structural AdaptationStructural Adaptation

Some organisms have body Some organisms have body structures that help them structures that help them certain in climates.certain in climates.

The fur of mammals is The fur of mammals is really hair that insulates really hair that insulates against the cold.against the cold.

Cacti have a thick, fleshy Cacti have a thick, fleshy stem that hold water,stem that hold water,

Cacti also have spiny Cacti also have spiny needles that also reduce needles that also reduce water loss.water loss.

Behavioral AdaptationsBehavioral Adaptations

Some behaviors help Some behaviors help organisms survive in certain organisms survive in certain climates. climates.

Rodents and certain Rodents and certain mammals undergo a period mammals undergo a period of decreased activity called of decreased activity called hibernation.hibernation.

They have a lower body They have a lower body temperature and lowered temperature and lowered body processes.body processes.

Other Behavioral AdaptationsOther Behavioral Adaptations

Bees huddle together Bees huddle together during cold weather.during cold weather.

On hot days, snakes On hot days, snakes hide under rocks.hide under rocks.

Desert turtles and Desert turtles and lizards obtain water lizards obtain water from their food.from their food.

EstivationEstivation

Lungfish survive periods Lungfish survive periods of intense heat by of intense heat by entering an inactive state entering an inactive state called estivation.called estivation.

As the weather gets hot As the weather gets hot and water evaporates, the and water evaporates, the fish will burrow into fish will burrow into mud and cover itseld in mud and cover itseld in mucus and mud and wait mucus and mud and wait until the weather until the weather improves.improves.

Human Behavioral AdaptationsHuman Behavioral Adaptations

Humans also exhibit Humans also exhibit behavioral adaptations.behavioral adaptations.

We shiver when we are We shiver when we are cold because the rapid cold because the rapid muscle movement muscle movement produces heat.produces heat.

We sweat when we a re We sweat when we a re hot because as the water hot because as the water evaporates, it takes evaporates, it takes some heat with it.some heat with it.

Chapter 17-3Chapter 17-3Climatic ChangesClimatic Changes

Objectives:Objectives: Explain what causes seasonsExplain what causes seasons Describe how EL Nino affects climateDescribe how EL Nino affects climate Explore the possible causes of climatic Explore the possible causes of climatic

change.change.

SeasonsSeasons

Seasons are short Seasons are short periods of climatic periods of climatic change.change.

Because the Earth is Because the Earth is tilted, certain areas of tilted, certain areas of Earth receive changing Earth receive changing amounts of radiation amounts of radiation throughout the year.throughout the year.

High LatitudesHigh Latitudes

During the year, the During the year, the high latitudes near the high latitudes near the poles have great poles have great differences in differences in temperature and temperature and daylight hours. daylight hours.

Short Term Changes in ClimateShort Term Changes in Climate

Some short-term changes may be the result of Some short-term changes may be the result of changes in ocean currents and global winds.changes in ocean currents and global winds.

Ocean currents help transfer heat to the Ocean currents help transfer heat to the atmosphere. This process generates global atmosphere. This process generates global winds. The global winds help move ocean winds. The global winds help move ocean currents. currents.

Any major change in an ocean current can Any major change in an ocean current can cause a change in climate. El Nino is an cause a change in climate. El Nino is an example. example.

Peru CurrentPeru Current

A cold current that A cold current that flows from west to east flows from west to east across the southern part across the southern part of the Pacific Ocean of the Pacific Ocean turns toward the equator turns toward the equator along the coast of South along the coast of South America and flows America and flows north along the coast of north along the coast of Chile and Peru. It is Chile and Peru. It is known as the Peru known as the Peru Current. Current.

El NinoEl Nino

Occasionally the Peru Occasionally the Peru Current is covered by a Current is covered by a thin sheet of warm thin sheet of warm water. Every 2 to 10 water. Every 2 to 10 years, strong winds years, strong winds spread the warm water spread the warm water over a large area over a large area resulting in droughts in resulting in droughts in some areas and flooding some areas and flooding in others.in others.

La NinaLa Nina

The opposite of el Nino is The opposite of el Nino is La Nina.La Nina.

During La Nina, the winds During La Nina, the winds blowing across the Pacific blowing across the Pacific are stronger than normal and are stronger than normal and warm water accumulates in warm water accumulates in the western Pacific. The the western Pacific. The water near Peru is colder.water near Peru is colder.

This causes droughts in the This causes droughts in the southern United states and southern United states and excess rainfall in the excess rainfall in the northwestern Untied States.northwestern Untied States.

Changes in ClimateChanges in Climate

The natural factors responsible for long term The natural factors responsible for long term climate changes are the slow drifting of the climate changes are the slow drifting of the continents, changes in the sun’s energy continents, changes in the sun’s energy output , natural catastrophic events and output , natural catastrophic events and variations in the position of the Earth relative variations in the position of the Earth relative to the sun. to the sun.

These natural factors are not related to human These natural factors are not related to human activity. The results of the human activity of activity. The results of the human activity of the burning of fossil fuels may also lead to the burning of fossil fuels may also lead to changes in climate.changes in climate.

Variations in Radiant EnergyVariations in Radiant Energy

During periods of high During periods of high energy output, the Earth’s energy output, the Earth’s temperature would rise. temperature would rise. The temperature would drop The temperature would drop during periods of low during periods of low energy output. energy output.

Scientists have found a link Scientists have found a link between sunspots activity between sunspots activity and climate change. During and climate change. During very cold periods there are very cold periods there are very few sunspots.very few sunspots.

Catastrophic EventsCatastrophic Events

Catastrophic events such as Catastrophic events such as meteorite collisions and meteorite collisions and volcanic eruptions can put volcanic eruptions can put tremendous amount of dust ash tremendous amount of dust ash and other particles into the and other particles into the atmosphere.atmosphere.

This in turn blocks sunlight This in turn blocks sunlight and cools the planet.and cools the planet.

Cities can also put up pollution Cities can also put up pollution that increases cloud cover that increases cloud cover downwind from the city. It downwind from the city. It also reduces rainfall in these also reduces rainfall in these areas.areas.

Changes in Earth Movement in Changes in Earth Movement in SpaceSpace

The shape of the Earth’s The shape of the Earth’s orbit can change. orbit can change. Sometimes it is more Sometimes it is more circular, sometimes more circular, sometimes more elliptical.elliptical.

The Earth’s tilt has varied The Earth’s tilt has varied from 21.5º to 24.5º. The tilt from 21.5º to 24.5º. The tilt changes about every 41,000 changes about every 41,000 years.years.

The Earth’s axis also The Earth’s axis also wobbles like a top.wobbles like a top.

Ice AgesIce Ages

Periods when much of the Earth’s surface has Periods when much of the Earth’s surface has been covered with enormous sheets of ice are been covered with enormous sheets of ice are called ice ages or major glaciations. called ice ages or major glaciations.

Scientists have found evidence of four major Scientists have found evidence of four major ice ages during the last 2 million years each ice ages during the last 2 million years each lasting between 60,000-100,000 years. The lasting between 60,000-100,000 years. The average temperature was 10-15ºC. average temperature was 10-15ºC.

The causes are not known but they are The causes are not known but they are probably associated with variations in the tilt probably associated with variations in the tilt of the Earth’s axis and/or the shape of the of the Earth’s axis and/or the shape of the Earth’s orbit around the sun.Earth’s orbit around the sun.

InterglacialsInterglacials

Interglacials are the time periods between Interglacials are the time periods between major glaciations. Interglacials are warm major glaciations. Interglacials are warm periods. During an interglacial, the average periods. During an interglacial, the average temperature was about 4 to 6 degrees higher temperature was about 4 to 6 degrees higher than the average temperature during a major than the average temperature during a major glaciation. A cold period called the Little Ice glaciation. A cold period called the Little Ice Age lasted from 1500 to 1900. Age lasted from 1500 to 1900.

Drifting ContinentsDrifting Continents About 230 million years About 230 million years

ago, all the Earth’s ago, all the Earth’s landmasses were joined in landmasses were joined in one super continent, one super continent, Pangaea. As the continents Pangaea. As the continents moved toward their present-moved toward their present-day locations, the sea level day locations, the sea level dropped, volcanoes erupted, dropped, volcanoes erupted, and much of the Earth’s and much of the Earth’s surface was pushed upward. surface was pushed upward. The combined effect was a The combined effect was a drop in temperature and drop in temperature and precipitation all over the precipitation all over the Earth. These changes were Earth. These changes were gradual.gradual.

Extinction of the DinosaursExtinction of the Dinosaurs

The climate change caused by the drifting of The climate change caused by the drifting of the continents may have resulted in the the continents may have resulted in the extinction of the dinosaur. Many types of extinction of the dinosaur. Many types of plants also became extinct. Dinosaurs that plants also became extinct. Dinosaurs that depended on these plants died. Meat-eating depended on these plants died. Meat-eating dinosaurs that depended on plant-eating dinosaurs that depended on plant-eating dinosaurs died. Other scientists believe that dinosaurs died. Other scientists believe that dinosaurs became extinct as the result of a dinosaurs became extinct as the result of a giant asteroid striking the Earth 65 million giant asteroid striking the Earth 65 million years ago.years ago.

GreenhouseGreenhouse

The greenhouse effect is a natural process that The greenhouse effect is a natural process that occurs when certain gases in Earth’s occurs when certain gases in Earth’s atmosphere trap heat and serve to warm the atmosphere trap heat and serve to warm the earth.earth.

When the Earth’s climate changes, the amount When the Earth’s climate changes, the amount of carbon dioxide that cycles among the of carbon dioxide that cycles among the atmosphere, ocean and land can also change.atmosphere, ocean and land can also change.

Greenhouse gases include water vapor, carbon Greenhouse gases include water vapor, carbon dioxide and methane.dioxide and methane.

Global WarmingGlobal Warming

In the mid-nineteenth century industrialization led to In the mid-nineteenth century industrialization led to the increased burning of fossil fuels, including coal, the increased burning of fossil fuels, including coal, oil and natural gas. Then these fuels are burned they oil and natural gas. Then these fuels are burned they release carbon dioxide that traps heat. Carbon dioxide release carbon dioxide that traps heat. Carbon dioxide has increased by 20% in the last 100 years. As a has increased by 20% in the last 100 years. As a result, the atmosphere becomes warmer, increasing result, the atmosphere becomes warmer, increasing 0.6º C in the last 100 years. 0.6º C in the last 100 years.

Deforestation may also contributes to global Deforestation may also contributes to global warming. warming.

Carbon CycleCarbon Cycle