ATMOSPHERE, CLIMATE, AND BIOMES

Chapter 5Climate and Terrestrial

Biodiversity

Atmosphere

Thin layer of gases that surrounds the EarthComposed of:

Nitrogen Oxygen Water vapor Argon Carbon dioxide Neon Helium Other

Atmosphere has changed

Early Earth’s atmosphere consisted only of methane, water vapor, ammonia and hydrogen

Photosynthesis greatly changed our atmosphere! What did this process add?

Five Layers

Troposphere

Earth’s surface to ~ 6 miles above the surface

Contains ~ 90% of atmospheric gases

Where weather occurs

Stratosphere

6 miles to about 30 miles above Earth’s surface

Air is less denseLess turbulent air flowContains the ozone layer

Mesosphere, Thermosphere, Exosphere

Gases become thinner and thinner

Colder and colderExosphere merges with outer space

What is the difference between WEATHER AND CLIMATE?

Solar Radiation

The sun is 93 million miles away, but it has a profound effect on our atmosphere’s temperature.

The sun’s energy comes in many forms Visible light passes through atmosphere UV light is absorbed by ozone Infrared radiation is absorbed by CO2, methane,

nitrous oxide, & water

What determines Climate?

LatitudeAir circulationOcean currentsLocal geography

Latitude

Distance from equator

Amount of solar energy an area receives depends on latitude

Tilt of Earth on Axis

Air Circulation Important properties of air:

Cool air sinks, and warms as it sinks Warm air rises, and cools as it rises Warm air can hold more water vapor than cool air

Solar energy heats the groundDue to these properties of air, winds are created

Air Circulation

Because different latitudes receive different amounts of solar energy, different patterns of air circulation are created…

These create the global patterns of precipitation

How do air circulation and pressure relate?

The Coriolis Effect

Winds move in a straight line, but the Earth rotates beneath them… creating a deflection Always to the left in the southern hemisphere Always to the right in the northern hemisphere

video

Fig. 5-6, p. 103

Cell 3 North

Moist air rises — rain

Cell 2 North

Cool, dryair falls

Cell 1 North

Moist air rises,cools, and releasesMoisture as rain

Cell 1 South

Cool, dryair falls

Cell 2 South

Moist air rises — rain

Cell 3 South

Cold,dry airfalls

Polar cap

Temperate deciduousforest and grassland

Desert

Tropical deciduous forest

Tropicalrain forest

Equator

Tropical deciduous forest

Cold,dry airfalls

Polar capArctic tundra

Evergreenconiferous forest

Temperate deciduousforest and grassland

Desert

60°

30°

0°

30°

60°

Winds

The air moving toward the equator from 30° N or S is deflected by the Coriolis effect to form a wind that comes dominantly from the east, easterlies. These easterlies are also called the trade winds

The air moving from 30°N or S to 60° N and S is deflected by the Coriolis effect to form a wind that comes dominantly from the west, westerlies.

Ocean Currents

Water holds large amounts of heatOcean currents are caused by winds and

rotation of EarthOcean currents influence climate by

distributing heat from place to place and mixing and distributing nutrients.

Upwellings- caused by ocean currents and pull nutrients from bottom of the ocean up

Ocean Currents

The easterlies push the ocean surface water across the ocean just north (and just south) of the equator, forming an equatorial current.

This equatorial current flows until it hits land. It is then deflected to the right in the northern hemisphere to form a western boundary current.

In the North Atlantic, this current is called the Gulf Stream.

Ocean Currents

Western boundary currents bring warm water from the equator to cooler, higher latitudes.

After flowing along the western side of the ocean, the current deflects again, crossing the ocean. It reaches the eastern side and deflects again, running back to the equator as an eastern boundary current.

Eastern boundary currents bring cool water from high latitudes toward the equator. In the Pacific, the eastern boundary current is called the California Current.

The uneven heating of the planet by the sun drives the atmospheric and oceanic circulation, which in turn causes the Earth's climate to vary by latitude. We recognize climate zones, from equator to poles:

• tropics • subtropics • temperate • polar

             

                                                              

EL NINO= WARMING LA NINA= COOLING

VIDEOA sudden change in

tropical winds warms coastal surface water, suppresses upwellings, and alters climate temporarily.

Cools coastal water and brings back upwellings.

Extreme Weather Changes

Geography of the land

Topography of the land can greatly affect climate

Continents are places for extra heating

Mountains shift winds upward and create added precipitation

Topography and Local Climate:Rain Shadow Effect

Interactions between land and oceans and disruptions of airflows by mountains and cities affect local climates.

Figure 5-8

Climate

There are many factors that determine your local climate, but ultimately it is… Latitude Air circulation Ocean currents Local geography

And the most important factor of all… SOLAR ENERGY!!

BIOMES: CLIMATE AND LIFE ON LAND

Different climates lead to different communities of organisms, especially vegetation. Biomes – large terrestrial regions characterized

by similar climate, soil, plants, and animals. Each biome contains many ecosystems whose

communities have adapted to differences in climate, soil, and other environmental factors.

BIOMES: CLIMATE AND LIFE ON LAND

Figure 5-9

Fig. 5-10, p. 107

Polar

Rain forestTropical

seasonalforest

Scrubland

Savanna Desert

TropicalGrassland

Chaparral

DeciduousForest

Coniferous forest

Desert

Temperate

SubpolarTundra

Wet

Cold

Dry

Ho

t

Desert Biomes

Deserts are areas where evaporation exceeds precipitation.

Deserts have little precipitation and little vegetation.

1. Tropical deserts are hot, dry most of the year with few plants, rocks and sand.

2. Temperate deserts have high day temperatures in summer, low temperatures in winter with more rain than in tropical deserts. Plants are widely spaced, mostly drought-resistant shrubs, cacti/succulents.

3. Cold deserts have cold winters, warm summers with low rainfall.

Desert plant and animal adaptations

Desert plants and animals have adaptations that help them stay cool and get enough water to survive. Adaptations include:

1. Plants that drop leaves during hot dry spells to survive in dormant state.

2. Plants may have no leaves, they store water in fleshy tissue, and open pores to have gas exchange only at night.

3. Some plants have very long taproots to reach groundwater.

4. Evergreen plants have thick, waxy leaves to reduce evapotranspiration.

5. Annuals store biomass in seeds that may be dormant for years.

Adaptations continued

6. Most animals are small. They may only come out at night or early morning. Others become dormant during extreme heat or drought.

7. Insects/reptiles have thick outer coverings to conserve water. Wastes are dry feces and concentrated urine.

8. Desert ecosystems are fragile and take a long time to recover from disturbances due to slow plant growth, low species diversity, slow nutrient cycling, and lack of water. Human impact on deserts due to overgrazing and off-road vehicles may take decades to overcome.

Tropical Grasslands (Savannah)Biomes

They have scattered trees and enormous herds of hoofed animals.

A savanna usually has warm temperatures, two long dry seasons with much rain the rest of the year.

1. Large herds of grazing (grass) and browsing (twig and leaf) animals feed here.

2. Competition for plant materials has been minimized due to specialized eating habits.

3. Human attempts to raise cattle on savannas, and the use of trees for firewood, have converted savanna to desert.

Temperate Grasslands

They have cold winters and hot and dry summers have deep and fertile soils that make them widely used for growing crops and grazing cattle.

They are widely distributed in North and South America, Europe, and Asia.

1. Organic matter accumulates, producing fertile soil, as aboveground plant parts die each year.

2. Soil held in place by network of intertwined root. 3. Natural grasses are adapted to fire. 4. North American grasslands are tall-grass prairies and short-grass

prairies. 5. Evaporation is rapid, winds blow most of the time and fires occur in

summer and fall. 6. Humans have used these lands to raise cattle and crops. They are

often flat areas, easily plowed. 7. Plowing makes soil vulnerable to erosion and blowing.

Polar Grasslands (Arctic Tundra)

Polar grasslands are covered with ice and snow except during a brief summer.

Long, dark winters and low precipitation.1. Under the snow there is a thick, spongy mat of low-

growing vegetation (grasses, mosses, dwarf woody shrubs)2. Most growth occurs within 6-8 weeks of summer

during the long hours of daylight.3. Permafrost is a permanently frozen layer of soil when

water freezes.4. Tundra is waterlogged during summer, with hordes of

insects.5. Migratory birds nest and breed in bogs and ponds

during summer.

Polar grasslands continued

6. Animals are mostly small herbivores such as lemmings, hares, voles that can burrow.

7. Predators include lynx, weasel, snowy owl and artic fox.

8. Decomposition is slow, soil is poor in organic matter

9. Human activities such as oil drilling, mining have scarred the landscape, which is very slow to recover.

Chaparral

Chaparral has a moderate climate but its dense thickets of spiny shrubs are subject to periodic fire.

Chaparral is found in coastal areas that border deserts.1. The winter rainy season is longer than in desert,

fog during spring/fall reduces evaporation.2. Low-growing, evergreen shrubs with occasional

trees is vegetation type.3. Fires move swiftly when started in these areas. 4. Humans like the climate (Southern Cali.) of this

biome, but risk losing homes to fire.5. Floods/mudslides occur after fires at times. WHY?

Tropical Rain Forest

Tropical rain forests have heavy rainfall on most days and a rich diversity of species occupying a variety of specialized niches in distinct layers.

Tropical rain forests are near the equator, and have hot humid conditions.

Dominant plants are broadleaf evergreens with shallow roots.

A dense canopy blocks most sunlight from reaching lower levels.

Vines often drape individual trees.Epiphytes such as orchids and bromeliads are found

on trunks and branches.

Tropical Rain forest continued

Most animal life is found in the sunny canopy layer of the forest.

Tropical forests cover about 2% of the land surface, but are habitats for about half the terrestrial species of earth.

Very little litter is on the forest floor because of rapid recycling of dead materials.

The acidic soil makes these areas poor places to grow crops or graze cattle.

So far at least 40% of these forests have been destroyed or disturbed by human activities.

Tropical dry forests are found in tropical areas with warm temperatures year round and wet and dry seasons.

Temperate Deciduous Forest

Temperate deciduous forests grow in areas with moderate average temperatures, abundant rainfall and long, warm summers.

Most of the trees in these forests survive winter by dropping their leaves, which decay and produce nutrient-rich soil.

Broadleaf, deciduous trees dominate this biome. More sunlight penetrates the canopy so there is

richer diversity of ground level plant life.A thick layer of leaf litter is usual due to fairly

slow decomposition.

Large predator species such as bear, wolves, wildcats, and mountain lions have been killed; deer and smaller mammals are now often the dominant species.

Large tracts of temperate forest have been cleared, planted in a single species of tree (tree plantations).

Bird species migrate to and from these areas to breed and feed. They are declining due to loss of habitat.

This biome has been disturbed by human activity more than any other terrestrial biome as a result of establishing settlements, industrialization, and urbanization.

Evergreen Coniferous Forest: Boreal Forest

Located in areas just south of arctic tundra around the northern sub-arctic regions of the earth.

These forests consist mostly of cone-bearing evergreen trees that keep their needles year-round to help the trees survive long cold winters.

Long, dry, extremely cold winters with 6-8 hours sunlight are the norm.

Summers are short with 19 hours of daily sunlight. Dominant trees are coniferous (cone-bearing) spruce, hemlock, fir,

cedar and pine. Decomposition is slow because of low temperatures, waxy narrow

leaves and high soil acidity. Soil is nutrient poor. Wildlife include bears, wolves, moose, lynx and many burrowing

rodent species. Acidic bogs form is summer. During summer birds feed on the many insects.

Temperate Rain Forest: Coastal Coniferous Forest

Coastal areas support huge cone-bearing evergreen trees such as redwoods and Douglas fir in a cool and moist environment.

Located along the western coast of Canada to northern California.

1. Most trees are evergreen with much moss and epiphytes.

2. There is a dense canopy with little light reaching the forest floor.

3. The winters are mild and summers are cool.

Mountain Biomes

Mountains are high-elevation forested islands of biodiversity.

Often have snow-covered peaks and gradually release water to lower-elevation streams and ecosystems.

Mountains are places with dramatic changes in altitude, climate, soil and vegetation within very short distances.

1. They are prone to erosion when vegetation is removed by natural disturbances, or human activities.

2. Mountains have important ecological roles such as habitats for endemic species, biodiversity, and sanctuaries for animal species driven from other habitats.

Mountains continued

3. They help regulate earth’s climate, snow peaks reflect much of solar radiation into space.

4. Mountains play a major role in the hydrologic cycle. (storing and releasing water)