Unit 1
Chapter 2
Section 1: Weather & Climate
A. Weather & Climate
1. Weather - the condition of the bottom layer of
the
earth’s atmosphere in one place over a
short period of time
- temperature, moisture, precipitation, wind
2. Climate – the weather patterns in an area over a long
period of time
***Usually described in Temperature & Precipitation****
- depends on elevation, latitude, location of nearby
landforms & bodies of water, wind & ocean
currents
*** Climate is what you expect, weather is
what you get!!
B. The Sun & the Earth
1. The Greenhouse Effect
a. Enough solar radiation reaches earth’s surface
to warm air & water
b. Atmosphere prevents heat from escaping back
into space too fast (similar to glass walls & roof
on a greenhouse) – allows warmth for plants
to grow
SECTION 1
Factors Affecting Climate
The Sun’s Effect on Earth
The Sun’s energy reaches Earth
Half of the energy is reflected back into space or absorbed by
the atmosphere.
The other half is absorbed by Earth’s surface and converted into
heat energy.
The atmosphere traps this heat in a process called the
greenhouse effect.
The greenhouse effect helps keep the planet warm.
c. Global Warming – a rise in earth’s temp.
caused by  amts of CO2 & other substances
– earth’s atmosphere traps heat from sun &
reflects it back to earth. As gasses build
up in atm., more heat trapped, global
temps rise.
- occurs naturally or by human action
* Global Warming could…
- partially melt ice caps causing rise in
ocean level + flooding of low-lying
areas
- increase precipitation in some
areas/decrease it in others
SECTION 1
The Solar System
Mercury
Earth
Uranus
Jupiter
Sun
Venus
Mars
Pluto
Saturn
Neptune
2. Rotation & Revolution
a. Rotation = the spinning motion of the
earth (like a top)
1) earth completes 1 rotation in 24
hrs
2) daytime – side that faces sun
3) nighttime – side facing away from
sun
b. Revolution = 1 complete orbit of the
earth around the sun
1) 1 revolution = 365 ¼ days
2) 4 x ¼ days = leap year
c. earth tilted on axis 23 ½º
1) “tropics” receive most direct sunlight
2) because of tilt, sunlight strikes diff.
parts of earth more directly at diff
times of yr.
3) when North Pole tilted toward sun,
northern hemisphere receives most
direct sunlight. When SP tilted
toward sun, southern hemisphere
receives most direct sun
4) these changes in SEASONS are
solstices – either of the 2 times of
yr when the sun appears directly
overhead at the Tropics of
Cancer 23 ½ºN /Capricorn 23 ½ºS
5) Equinox – either of the 2 times/yr
when day & night are of nearly =
length everywhere on earth – sun
appears directly overhead equator
Reason for the seasons
C. Precipitation
1. Precipitation vs. Humidity
a. Humidity – amt of water vapor in atmosphere
b. Precipitation – all forms of water that fall from
the atmosphere to earth’s surface
1) forms as air temp changes
- warm, less-dense air absorbs more
moisture than cool
- when air cools, can’t retain water
vapor, so condenses as liquid cools
2) occurs when more water collects in
clouds than they can hold
Forms of Precipitation
The Water Cycle
2. Types of Precipitation
a. Convectional Precipitation - occurs when hot,
humid air rises from the earth’s surface,
cools, loses ability to hold water
- common at equator/tropics
b. Orographic Precipitation – occurs when
warm, moist air forced upward over high
landforms (RAINSHADOW)
- common on seacoasts
- warm winds cool as they rise over mt
clouds form, rain/snow
- air cool & dry on other side of mt
*** Cascades/Sierra Nevadas
Rainshadow
c. Frontal Precipitation – (most common) –
occurs when 2 fronts (air masses of diff.
temps) meet. Warm air forced up by heavier,
cooler air. As rising warm air cools, frontal
precipitation forms
D. Influences on Climate (temp & precipitation)
1. Latitude
a. sun’s rays fall most directly at or near equator,
less direct toward poles – most place near eq.
have warm climates – most near poles have
colder climates
b. distance from eq. used to ÷ world into zones
1) Tropics = btwn 23 ½º N/S & the Eq.
- hot all yr
2) Temperate = 23 ½º N/S to 66 ½º N/S
- wide temp. range
3) Polar = 66 ½º N/S to NP/SP
- cool to bitterly cold
Climate Zones
2. Wind & Ocean Currents
a. Heat distributed via convection – the transfer
of heat from one place to another
- warm gases/liquids are lighter/less
dense than cooler
- warm gases/liquids rise, cooler sinks &
displaces lighter/ warmer materials
- warm air/water flows from eq. to poles
- cold air/water flows toward eq.
b. Wind
1) winds move from high to low pressure.
Mvmt of wind distributes sun’s heat over
earth’s surface
- low pressure = rising warm air
- high pressure = falling cool air
2) Coriolis Effect – b/c earth rotates, winds
are deflected (bend)
- NH = wind curves right
- SH = wind curves left
3) Wind Patterns: temp + pressure =
pattern of prevailing (dominant) winds
- Doldrums – area near equator
with calm/light breezes – warm air
rising
- Horse Latitudes - ~ 30ºN/S
with unpredictable winds – cool air
sinks
(Called Horse Lats b/c Spanish sailors sometimes had trouble getting
enough wind to travel in that area, so when traveling to America, they
threw their horses overboard to lighten ships/gain speed
- Trade Winds – btwn Horse-Equator
predictable winds blow toward Eq.
from NE & SE
(called trade winds b/c merchant trading ships depended on them to push
heavy-laden ships across ocean)
Wind Currents
c. Ocean Currents – via convection, ocean
waters help distribute heat: carry warm water
from tropics to poles or cool water from poles
toward equator. ** wind + coriolis effect
influences circular patterns of ocean currents
3. Nearby Bodies of Water
a. Land temps can change quickly &
dramatically; water slower ; so, temps of
lrg bodies of water affect surrounding
climate
- winds that blow over water take on water
temp
- thus, usually milder temps in coastal
regions than at other areas in the
same latitude
- British Isles = mild climate
b. Areas away from influence of water, interior
of continents, experience continental climates
4. Elevation
a. Affects climate more than its latitude position
b. As elevation increases, temps decrease
c. Can have snow-capped mts in the tropics
Look! Snow!
Mt. Kilimanjaro – Tanzania – latitude?
5. Nearby Landforms
a. no climate is ever uniform
b. Areas can be affected by landforms such as
coastal mts, lakes, forests, & even a
concentration of tall bldgs. Thus, city temps
usually little warmer than surroundings
E. World Climate Regions – see chart
F. Climate Graphs
- consist of a line graph (temperature) & a bar
graph (precipitation)
- Climate graphs present the Average Monthly
Temperature and Average Monthly Precipitation
of a specific place
- Climate graphs also enable you to compare
climates in different cities
Section 2: Ecosystems
A. Introduction
1. Ecosystem – formed by the interaction of plant
life, animal life, and the physical environment in
which they live
- can be affected by climate, sunlight,
temperature, precipitation, elevation, soil,
landforms
- change in one aspect of an ecosys. can
lead to changes in others (ex. Loss of
oak trees can affect squirrels)
2. Biome – term used to describe a major type of
ecosystem that can be found in various regions
throughout the world – a classification system
- see chart
• Another way to visualize major land biomes is to
compare them based on their average temperature
ranges and rainfall levels, which shows how these
variables combine to create a range of climates
Tropical Rain Forrest
• Amazon River Basin
• Congo River Basin
• Dense multilayered canopy/broad leaf
evergreens
Mid Latitude Forest
• Much of U.S.
• Deciduous- Loose their leaves
Coniferous Forest
• East Texas Piney Woods/ Colorado
• Northern Forests/ Taiga- Cooler climates
Grasslands
• Temperate- Grasslands in the cooler part of
the world. Great plains or prairies of U.S. and
Steppes of Eurasia
• Tropical Grasslands- Equatorial grasslands
called savannas
• Herbivores
• Carnivores
Deserts
• Dry barren region with specialized plants and
animals.
Tundra
• Temperatures always cool or cold
• Small plants (specialized)
• Permafrost