Transcript Climate and Vegetation Chapter 3

Chapter 3
Climate and Vegetation
I. Seasons and Weather
A.3 factors cause seasons and control
the amount of solar energy that
falls on different parts of the earth
1. Rotation
a.One complete spin on Earths
axis (24 hours)
b.Allows for warming and
cooling of surface
2. Revolution
A. 365 ¼ days for Earth to
revolve around Sun
3. Tilt
A. Axis is tilted 23 ½ degrees
Combination of revolution and
tilt causes changing seasons
A.Solstice – Earth’s axis points at greatest
angle towards or away from the sun. It
marks the beginning of winter/summer.
B.Equinox – Latin for “equal night” occurs
when axis is not pointed towards or away
from the sun. It marks the beginning of
autumn/spring.
B. Weather – condition of the atmosphere at
a particular location & time
1. Daily weather is complex result of
several conditions
a. Water vapor – most is from
evaporation of oceans
1. W/o water vapor, could be no
clouds, rain or storms
2. Humidity – amount of water vapor
in air
3. Condensation – water vapor
changes from gas to liquid
a. seen as fog, clouds or dew
b. if condensation gets big
enough, it falls as precipitation
b. Elevation –
1. As elevation (height above sea
level) increases, the temperature
decreases
2. Every 1,000 ft. increase in
elevation yields a 3 ½ degree drop in
temp.
3. With increased elevation, air
becomes thinner and loses ability to
hold moisture
Landforms & bodies
of water
Winds – move solar
energy & moisture,
resulting in rapid
weather changes
2. Types of precipitation
a. Convectional – warm,
humid air is heated by the sun
and rises (convection)
As it rises, the water vapor
cools, condenses, and falls
as precipitation
b. orographic
• Moist air from the ocean meets a
mountain barrier & the air is
forced to rise
• the windward side of the
mountain gets a great deal of
precipitation
• leeward side of mountain gets a
little moisture from the warming,
c. Frontal
1. Front is a boundary between
2 air masses of different
temperatures and densities
2. Rain/snow occurs
when lighter, warm air
is pushed up over
colder, dense, air
C. Weather Extremes – called storms,
occur when energy stored in the
atmosphere is released
1. Hurricanes – (aka: Typhoons) form
over warm ocean waters & carry
violent winds, torrential rains, and
storm surge (wall of water pushed on
shore by the wind)
a. Winds up to 200 mph and storm
surges to 20 ft.
2. Tornadoes – twisting spiral
column of air that forms quickly
& w/o warning
a. Born from strong thunderstorms
b. winds may reach 300 mph
c. US has most tornadoes in the
world (avg. 700/yr and ¾ of all
tornadoes occur in the US)
3. Blizzard – heavy snow
storm w/ winds more than 35
mph and greatly reduces
visibility
4. Droughts – long period time
w/o rain or minimal rainfall
5. Floods – when water spreads
over land not normally covered
by water
II. Climate – term for weather
conditions at a particular location
over a long period of time
A.4 major factors influence climate
(wind/ocean currents, latitude,
elevation, topography)
1. Air pressure & wind – the force
exerted by air is called air
pressure
a. Air pressure creates the winds
and ocean currents that exchange
the globe’s energy
b. when air is warmed, it expands,
becomes lighter, and rises (known
as convection) thus forming a low
pressure area. Low pressure tends
to bring unstable weather
C. Cold air is dense, heavy, and
tends to sink, causing High
pressure. High pressure causes
clear, calm weather
2. Wind is the horizontal motion of air
between areas of different pressure
3. Major Air Pressure zones
A. Equatorial Low – intense heating
at the equator
B. Subtropical High – around 30° N
and S
C. Sub polar low–about 60 ° N and S
D. Polar High
B. Global Warming
1. The measurement of heat in Earth’s
atmosphere is called temperature.
2. The process of heat energy being
trapped by the atmosphere, keeping
Earth warm is called the Greenhouse
effect.
3. CO2 and other heat trapping gases are
increasing in the atmosphere due to the
burning of fossil fuels (coal and oil)
III. World Climate Regions
A. Defining a Climate Region
1. Most significant factors in defining
a climate are temperature and
precipitation
2. Other factors are: location on the
continent (continental or maritime),
topography, and elevation
B. Types of Climates
1. Tropical Wet
A.avg. temperature 80 ° F yr. Round &
more than 80 in. of rain per year
2. Tropical Wet and Dry
A. rainy season in summer and dry
season in winter
B. found next to tropical wet and dry
climates
3. Semi Arid
A. about 16 inches rain/yr
B. summers are hot and winters are
mild
C. Found in interior of continent or next
to deserts
4. Desert
A. receive less than 10 in. of rain per
year
B. can be hot or cold; most occur
around 30 ° North or South
5. Mediterranean
A. summers are hot and dry;
winters are cool and rainy
B. example – land around
Mediterranean Sea, southern
California
6. Marine West
Coast
A. located close to
the ocean, foggy,
cloudy, and damp
B. Northwest US
and Western
Europe
7. Humid Sub Tropical
A. Long hot summer and humidity,
mild to cool winters
B. Southeast US and east coast of
continents
8. Humid Continental
A. great variety of
temperatures and
precipitation
B. 4 distinct seasons; located
in mid-latitude interior of
Northern Hemisphere
continents
9. Sub Arctic
A. evergreen forests called tiaga
cover sub arctic areas
B. greatest temperature differences
from winter to summer of all
climates
C. short, cool summers, winter,
very cold – below freezing for 5 –
8 months of yr
10. Tundra
A. flat, treeless land around Arctic
circle
B. less than 15 inches of rain/yr;
summer lasts only a couple of
weeks – temps. Only reach 40°F.
C. has permafrost, subsoil is
constantly frozen year round
11. Ice Cap
A. snow, ice,
permanently
freezing
temperatures
12.Highland
A. Climate varies with latitude, elevation, etc.
In Mountainous areas depends on if a slope
faces north or south, cold winters, warm
summers. Ex. Rocky Mts.
IV. Soils and Vegetation
A. Vegetation Regions
1. Ecosystem-interdependent
community of plants and
animals
2. Biome – the ecosystem of a
region
A. forest
1. Deciduous, coniferous, or
mixed
2. Almost exclusively in N.
Hemisphere
B. Grassland – mostly flat land
dotted with few trees
1. In tropical areas, often
called a savanna
2. In N. Hemisphere, called
steppe or prairie; S. America
called a pampas
c. Desert
1. Plants that can conserve
water and withstand heat
d. Tundra
1. Only plants
such as lichens
and moss can
survive the
cold, dry
climate