Chapter Three
Climate and Vegetation
WHERE DO SEASONS COME FROM?
Earth rotates on it’s axis at a 23.5 degree angle in relation to the sun
Earth rotates once every 24 hrs
Earth makes one revolution around the sun every 365.25 days
SEASONS Earth’s axis always points to
the same spot in the sky Revolution and tilt cause the
seasons (different parts of the earth
receive direct rays from the sun for more hours at certain times of the year)
Season Diagram
WHAT CAUSES WEATHER?
Amount of solar energy How air masses absorb and
distribute the energy Landforms / bodies of water Water Vapor (determines if there
will be precipitation) Cloud cover Elevation
PRECIPITATION
Convectional-
Orographic-
Frontal-
WEATHER EXTREMES Hurricanes
• form over warm tropical waters, takes days to develop
• can cover 100’s of miles• winds from 75- 200 mph
Tornadoes• develop very quickly• wind speeds up to 300
mph• small diameters
(about 300 ft.)• can stay on ground for
hours• can cause massive
damage
WEATHER EXTREMES
WEATHER EXTREMES
Blizzards- heavy snowstorms; winds more than 32 mph; reduced visibility
Droughts- long period of time without water; leads to crop failures and water shortages
Floods- when water flows over land faster than the land can absorb it
CLIMATE FACTORS
Zones of latitude• Low or Tropical
• Middle or Temperate
• High or Polar
El Nino
Warming of the waters off the coast of South America
Occurs about every 2-7 years Prevailing easterly winds slow or
reverse direction changing the ocean’s temperature
This affects weather worldwide
El Nino
Normally easterly winds bring rain and push warm ocean toward Asia and Australia
In El Nino years, winds push warm water and heavy rains toward Americas. We get floods and Australia and Asia get droughts
La Nina
Occurs when the winds blow opposite El Nino
Winds blow the warmer water to the lands on the western Pacific Rim
Causes increased rain in India and drought along Pacific coast of USA
WORLD CLIMATE REGIONS
Two most significant factors in defining different climates are:
• Temperature
• Precipitation
CLIMATE GRAPHS
SOILS AND VEGETATIONS
World’s food supply grows in the top 6 inches of soil, topsoil.
Type of vegetation is determined by the depth, mixture and humus content of the soil.
VEGETATION REGIONS
Vegetation patterns are identified by the ecosystems they support.
The ecosystems of a region, (biomes) are divided into:Forest GrasslandDesert Tundra
FORESTS
Categorized by the types of trees they supportBroadleaf (i.e. Maple & oak called deciduous)Rain forest is covered with broad-leafs
Needle-leaf (i.e. Pine and fir called coniferous)
GRASSLANDS
Savannas in tropical regions Steppes in Northern
Hemisphere Many names in South
America – Pampas, Cerrado, Llanos
Tundra- plants like lichen and mosses are specially adapted to grow there in dry, cold conditions
Desert- plants must be able to conserve water and withstand heat. Plants like cacti and sagebrush are good there.