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.