CHAPTER 3 – CLIMATE & VEGETATION
I. Seasons & Weather
A. Seasons
1. Earth’s Tilt
 Northern ½ of the earth tilts toward the sun in summer
 Northern ½ of the earth tilts away from the sun in winter
 Solstice – day when the sun appears directly overhead at the Tropics
of Cancer & Capricorn
o Winter Solstice ( Dec. 22 or 23) – beginning of winter;
shortest day of the year
o Summer Solstice ( June 21 or 22) – beginning of summer;
longest day of the year

Equinox – the days & nights all over the world are equal in length
o Marks the beginning of spring ( Mar. 21) & fall ( Sept. 23)
B. Weather
1. Climate - long term weather conditions
2. Weather – day to day changes in atmospheric conditions
 Factors that cause the weather:
o Water vapor – precipitation
o Cloud cover
o Landforms & Bodies of Water
 Water heats slowly and loses heat slowly
 Land heats quickly and loses heat quickly
o Elevation
o Air movement
 Types of Precipitation:
Convectional
Sun heats the air,
warm air rises
Windward side of
the Mountain
Orographic
Mountains block the passage
of air and cause it to rise
Leeward side of
the Mountain
Rain
Shadow
Graphic created by EJoyce
Frontal
Cold, dense air pushes up
warm, light air
Rain Shadow – land on the leeward side that
gets little rain from the descending dry air.
C.
Weather Extremes
 Hurricanes – storms that form over tropical ocean waters
o Known as Typhoons in Asia
 Tornadoes – powerful funnel-shaped column of spiraling air
 Blizzards – heavy snowstorm
 Droughts – long period of time without rain
 Floods – when water spreads over land not normally covered with water.
II. Climate
A.
Factors Affecting Climate
1. Wind Currents
o Heat is distributed by a process called convection – the transfer
of heat in the atmosphere by upward motion of air
o Global Wind Currents: Polar Easterlies, Westerlies,
Northeasterly Trade Winds, Southeasterly Trade Winds
o Hot air flows toward the poles; cold air moves toward the
equator
o Winds are identified by the direction from which they blow
2. Ocean Currents
 Water of the oceans also help distribute heat
 Affect not only the temperature of an area, but also the amount of
precipitation received
 Warm water flows toward the poles; cold water moves toward the
equator
3. Zones of Latitude
 Geographers divide the Earth into 3 zones:
90
HIGH
Arctic Circle
66 1/2
MIDDLE
Tropic of Cancer
LOW
23 1/2
Equator
0
Tropic of Capricorn
23 1/2
MIDDLE
Antarctic Circle
66 1/2
HIGH
Graphic created by EJoyce
90
- Tropical Zones (low latitude) – found on either side of
the equator – Tropic of Cancer & Tropic of Capricorn
o Lands are hot all year
- Temperate Zones (middle latitude) – found between the
tropics and polar regions
o Climates vary from relatively hot to relatively cold
- Polar Zones (high latitude) – Encircle the North & South
Poles
o Area is cold all year
4. Elevation – distance above sea level
o As altitude increases, air temperature decreases
 Climate gets colder, the higher the elevation
5. Topography – landforms that affect climate
o Inland mountains, large desert areas, lakes, forests, and other
natural features can influence climate
B. Changes in Climate
 El Niño – warming of the waters off the west coast of South America
o Occurs every 2 to 7 years
o Can cause floods and mudslides
 La Niña – winds blow warmer water to the lands on the western Pacific rim
o Causes droughts
 Global Warming – increasing air temperatures
o Some scientists believe it is caused by the Greenhouse Effect
III.
World Climate Regions
A. Defining a Climate Region
 Temperature & Precipitation are 2 major factors that define climate regions
 Other factors are: location on a continent, topography, & altitude
 5 general climate regions are:
1. Tropical (low latitude)
2. Dry
3. Mid-latitude
4. High latitude
5. Highland
B. Types of Climates
1. Tropical Wet – always hot; rainfall daily
2. Tropical Wet & Dry – rainy, warm summers; dry, cool winters
3. Semiarid – hot summers; mild to cold winters; not much rain
4. Desert – less than 10 in. rain per year; temp. drop at night
5. Mediterranean – dry, hot summers; cool, rainy winters
6. Marine West Coast – cloudy, foggy, damp; even distribution of
precipitation throughout the year
7. Humid Subtropical – long periods of summer heat & humidity;
mild to cool winters
8. Humid Continental – variety in temp. & precipitation; 4 seasons;
changing weather conditions
9. Subarctic – huge temp. variations between summer & winter;
short, cool summers; long, very cold winters
10. Tundra – very little precipitation; (permafrost) subsoil always
frozen; very short, cool summers;
11. Ice Cap – Snow, ice, and permanently freezing temps.; less
than 10 in. precipitation per year.
12. Highlands – climate varies w/ latitude, elevation, topography,
continental location
IV. Soil & Vegetation
A. Soil Regions
 Soil – thin layer of weathered rock, humus, air, and water
 Factors that determine the type of vegetation that can be supported in
a region are: depth, texture, and humus
 Soil characteristics & climate are major influences in vegetation regions
B. Vegetation Regions
 Natural environments for human activities such as farming, raising
livestock, and producing timber
 Soil, temperature, and moisture influence the type of vegetation that
thrives naturally in the region
 Ecosystem – interdependent community of plants & animals
 Biome – ecosystem of a region
o Types of Biomes:
1. Forestlands – regions categorized by the type
of trees they support – broadleaf or needleleaf
 Deciduous trees – broadleaf trees such as maple, oak,
birch, and cottonwood
o Rain Forest located in the tropical zone and is
covered with a heavy concentration of
broadleaf trees.
 Coniferous trees – needleleaf and cone bearing trees
such as pine, fir, and cedar
2. Grasslands – flat regions with a few trees
 Tropical grassland region, the flat, grassy, mostly
treeless plains are called savanna
 Northern Hemisphere, the terms steppe or prairie
are used to identify temperate grasslands
 Southern Hemisphere, the temperate grasslands may
be referred to as pampas
3. Desert – has plants that can conserve water and
withstand heat, such as cacti, sagebrush, or
other shrubs
4. Tundra – plants that hug the ground, such as
mosses and lichen are best able to survive the
cold dry climate