Chapter 2 - Climate and Vegetation

Chapter 2, Section 1 - Weather and Climate 

I.                   Weather and Climate

*Weather – the condition of the bottom layer of the earth’s atmosphere in one place over a short period of time.
*Atmosphere – a multilayered band of gases, water vapor, and dust above the earth
*Describing weather – terms used – sunny, cold,
*Climate – the term for weather patterns that an area typically experiences over a long period of time
*Climate factors are / can be:
    a.      elevation
    b.     latitude
    c.     location in relation to nearby landforms
    d.     location in relation to bodies of water

*Old Farmer’s Saying “Climate is what you expect; weather is what you get.”

 II.                The Sun and the Earth

*Earth 93 million miles away from sun – what would happen if we were any closer or farther away?

a.                  The Greenhouse Effect

*Small amount of solar radiation reaches the earth’s atmosphere
*Radiation is reflected back into space by the atmosphere and the earth’s surface – enough remains to warm the earth’s land and water
*Atmosphere prevents heat from escaping back into space
*The atmosphere traps the sun’s warmth for growing plants – therefore Greenhouse Effect
*Not all locations get the same amount of heat and light from the sun
*Day and night, seasonal change, and differing climates are all largely determined by the relative positions of the sun and the earth

b.                 Rotation and Revolution (p. 60)

*Rotation is the earth moving through space as it spins on its axis like a top
*Earth completes one rotation every 24 hours
*Side that faces the sun is day – night is away from sun
*Earth orbits around the sun
*Revolution is one complete orbit around the sun
*Earth completes one revolution every 365 ¼ day – length of 1 year
*Every four years we have a “leap year”
*Earth does not revolve around the sun in a straight up and down position, but tilted at 23 ½ º angle
*Tropic of Cancer – 23 ½ ºN
*Tropic of Capricorn -   23 ½ ºS
*Mark the boundaries where places on earth receive the most direct sunlight
*Solstices (Winter – Dec. 21 and Summer – June 21) the days when the sun appears directly overhead a the Tropics of Cancer and Capricorn
*Equinoxes (Fall – Sept. 23 and Spring – March 21) the sun, at noon appears directly overhead at the Equator.  Around these dates, the lengths of day and night are nearly equal everywhere on the Earth

c.                 Latitude and Climate

*The angle of the sun’s rays affect weather and climate in other ways
*Geographers use latitude from the Equator to divide the world into zones.
*There are three zones: (p. 62)

a.      Tropic zones are in the low latitude zones which are from 23 ½ ºN to 23 ½ ºS

b.     Temperate zones are in the middle latitudes which are 23 ½ºN to 66 ½ºN AND 23 ½ºS to 66 ½ºS

c.     Polar zones are in the high latitudes which are from 66 ½ºN and above AND 66 ½ºS and above

III. Distributing the Sun's Heat 

    * Heat is distributed by a process called convection – the transfer of heat from one place to another
    *Convection is when warm gases and liquids are lighter or less dense than cool gases and liquids
    *Process takes place in both air and water
    *Movements of air are called wind
    *Movements of water are called currents
    *Warm air and water both flow from the equator to the poles
    *Cold air and water both move from the poles to the equator

a.                  Wind (p. 60)

*Wind - atmospheric pressure is the weight of the atmosphere overhead
*Rising warm air creates areas of low pressure
*falling cool air causes areas of high pressure
*Winds move from areas of high pressure into areas of low pressure
*Wind movement worldwide redistributes the sun’s heat
*Because the earth rotates, winds move in a bending (deflecting) current
*The deflection is called the Coriolis Effect
*Northern Hemisphere the wind curves to the right
*Southern Hemisphere the wind curves to the left

b.                 Wind Patterns

*“Doldrums” – Equator has rising warm air which causes calm weather / very light, variable breezes – this region has very light winds
*“Horse Latitude” - 30º North and South – cool air sinks to earth making travel by ship difficult – Spaniards gave name when they dumped their horses overboard to lighten the ships load and to move faster
*“Trade Winds” – Between the Equator and “Horse Latitudes” wind blow steadily toward the Equator from the Northeast and Southeast – Merchant trading ships depended on these winds to push them across the ocean

 c.                 Currents (p. 63)

*Waters of the oceans also help to distribute heat
*Water patterns follow similar wind patterns
*Wind and the Coriolis effect influence the circular patterns of currents in the oceans

 IV.            Precipitation (p. 65)

*Humidity – amount of water vapor contained in the atmosphere
*Precipitation – is all forms of water that fall from the atmosphere onto the earth’s surface
*Timing and volume of precipitation are important aspects of climate
*Precipitation forms as air temperature changes
*Precipitation occurs when more water collects in clouds then they can hold
*Precipitation is divided into three types: Convectional, Orographic, and Frontal

 a.                  Convectional Precipitation

*Occurs when hot, humid air rises from the earth’s surface and cools, thereby losing its ability to hold much water
*Common near the Tropic Zones
*Produce nourishing rainfalls that feed lush, tropical forest

b.                 Orographic Precipitation

*Occurs when warm, moist air is forced upward when passing over high landforms

*Common on seacoasts where moist, ocean wings blow towards coastal mountains

*The land on the leeward side of the mountain (away from the wind) lies in what is called a rain shadow

*California’s Mohave Desert lies inland behind the Sierra Nevada

c.                 Frontal Precipitation

*Occurs when two fronts (air masses) of different temperatures meet

*Most common kind of precipitation

V.               Other Influences on Climate

*Temperature and precipitation are the major factors affecting weather and climate
*There are other influences

a.                  Nearby Bodies of Water

*How they absorb heat is very different from land
*Ocean temperatures vary less than 10º throughout the year
*Play major part in affecting surrounding climate
*Marine Climates – Pacific Coast and in Southern Chile – also British Isles and Western Europe *Continental Climates – away from the influence of the oceans, the great central areas of continents in the Northern Hemisphere
*These areas have cold, snowy winters and warm / hot summers – humidity and precipitation vary and temperatures range in extreme hot and cold
*Regions in the continental climate are between mild and polar climates
*Central Europe, Northern Eurasia, parts of China, and most of North America have continental climates

b.                 Elevation

*Has a dramatic effect on climate in highland areas throughout the world
*Air temperature decreases at a rate of about 3.5ºF for every 1,000 feet in elevation

 c.                 Nearby Landforms

*Inland mountains, large desert areas, lakes, forests, and other natural features can influence climate – even tall buildings
*Pavement and concrete absorb the heat  

 VI.            World Climate Regions (p. 66 & 67)

*Many different classification systems to define the world’s major climate regions

*Difficult to define because of changing climate conditions

*Most efforts to classify climate regions rely on two factors: temperature and precipitation
*Six broad types of climate regions – Tropical, Dry, Moderate, Continental, Polar, and Highland (p. 68)

 VII.         Changing Climates

     *Climate changes result from changes in nature, which is caused by human action
    *Pollution (carbon dioxide and other substances) in the earth’s atmosphere are causing our “global warming”
    *Global warming includes and increases in precipitation in some areas and a decline in others

Chapter 2, Section 2 - Vegetation Regions

I.                   Plant Communities

*Plant Community is the mix of interdependent plants that naturally grow in one place
*Environment – the physical conditions of the natural surroundings
*Climate, sunlight, temperature, precipitation, elevation, soil, and landforms are all part of the plant environment

 a.                  Biomes and Vegetation Regions

*Biome (BY om) is used to describe a region in which the environment, plants, and animal life are suited for one another
*Geographers also classify regions by – Natural Vegetation or the typical plant life in areas where humans have not altered the landscape significantly
*Vegetation regions are of four general types: forest, grassland, desert, and tundra
*Besides climate, soil type, slope, and drainage all play a part in the kind of vegetation found in each region

II.                Forest Regions

 *Every continent has forest vegetation except Antarctica

a.      Tropical Rain Forest
*Area near the Equator because of warmth and rainfall
*Largest rain forest is in the Amazon River Basin in South America
*2^nd largest rain forest is in Indonesia / Asia
*3^rd largest rain forest is in the Congo River Basin in Africa
*Tall trees with dense, green, canopy of leaves that block out the sun from the forest floor
*Known as broad leaf evergreens

b.     Mid-Latitude Forest

*Deciduous trees shed their leaves during one season
*Depending upon the season, they look very different
*Broadleaf deciduous (oak, birch, maple) forests once covered much of Europe, eastern North America, and eastern Asia
*Large part cut down for furniture, house, etc…
*Some have tried to replant what was lost and others have let the land renew itself
*The Middle Latitudes temperature climate usually has adequate rainfall, warm summers, and cold winters

c.     Coniferous Forest

*Colder parts of Middle Latitudes have coniferous forest
*Coniferous – the cones that carry and protect their seeds
*They DON”T have leaves, they HAVE needles which are long and thin
*Needle trees / Evergreens can take the winter
*Coniferous (pines, spruces, firs) forests cover huge areas in Northern America, Europe, and Asia

             d.     Other Forest Types

*Forest regions do overlap in many regions
*A mixed region has coniferous and broad leaf deciduous trees growing together in the same area
*Chaparral (another forest type) includes small evergreen trees and low bushes or scrub
*Spanish word for “an area of small evergreen oak trees”
*Uniquely adapted to a Mediterranean climate
*Chaparral plants have leathery leaves to hold moisture over the dry summer
*Chaparral regions are found on the coast of the Mediterranean Sea, southern California, Chile, South Africa, and Australia and even parts of the Southwestern part of the U.S.

III.             Grasslands

* Central regions of several continents are covered by grasslands

 a.      Tropical Grasslands

*Savannas – huge tropical grasslands that grow nearest the Equator
*Savannas have three distinct seasons: wet, dry, and “wildfires that occur naturally”
*Wildfires are necessary because they help new grass to grow

b.     Temperate Grasslands

*Grasslands in the cooler parts of the world are known by several names
*Different lengths and kinds of grass because of climate and precipitation
*North America – praries
*Northern Eurasia and centeral Asia – steppes
*Steppe is Russian meaning “treeless plain”
*Argentina – pampas
*South Africa - veld

 IV.            Desert Vegetation

*Deserts not just sand or soil – many plants have adapted to survive w/o water
*Cactus plants store water in thick stems – some expand to hold water
*Cactus needles protect their water supply from animals
*Other plants have small leaves, and others have seeds which help them to survive this climate
*These plants have short life cycles because after a rain they will sprout, grow, flower, produce seeds, and die in a short period
*Desert plants grow widely scattered because of the lack of water

V.               Tundra

*Tundra regions – temperatures are always cool or cold
*Specialized plants grow in these regions
*Many types of Tundra

a.      Alpine Tundra

Exists in high mountains – no trees grow, but small plants and wildflowers grow in sheltered spots

Lichens – brightly colored plants that make patterns on the rock

b.     Arctic Tundra

Plants must be able to live in cold temperatures and short growing seasons
Need to go without sunlight for most of the winter
Landscape – treeless, covered with grasses, mosses, lichens, and some flowering plants

* Permafrost – layer of soil just below the tundra surface that stays permanently frozen
*Extreme climate regions vegetation is rare i.e. Parts of Greenland and Antarctica - However, small and simple plants do survive in some areas

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