2. What is the difference
between weather & climate?
Weather is the state of
the atmosphere at a
particular place at a
particular moment.
Ex: it is raining outside
today.
Climate is the long-term
prevailing weather
conditions at a
particular place based
upon records taken.
Ex: it is hot and humid in
the southeast during the
summer months.
3. What factors determine
climate?
Latitude
Atmospheric
circulation patterns
Oceanic
circulation patterns
Local geography
Miscellaneous
Solar activity
Volcanic activity
4. Latitude
Distance from the equator
measured in degrees north or
south.
Low latitudes: near the equator
(0°) and about 30° above and
below.
Gets most sunlight, night & day
are about 12 hrs each,
temperatures are high year round
and no summers or winters
High latitude: from about 30°
latitude to the north & south pole
(90°).
Gets less sunlight, night & day vary
during summer & winter,
Summer- 12 hrs daylight in our
area; 2-4 hrs of nighttime at poles
Winter- 8 hrs daylight in our area;
24 hrs; 2-4 hrs of daylight at poles.
5. Atmospheric Circulation
3 important properties of air:
Cold air sinks, compresses,
and warms b/c it is denser
than hot air.
Warm air rises, expands, and
cools as it rises.
Warm air can hold more
water vapor than cold air.
As warm air cools it
condenses and makes rain
The rotation of these 3
properties creates wind.
Uneven heating of Earth &
Earth spinning alter the
movement of wind on Earth
and create wind patterns.
6. Atmospheric Circulation
Global Circulation Patterns
At equator, cool air cannot
sink due to all the warm air
rising up.
This cool air is forced away
from the equator & moves
toward the poles.
At about 30° N and S of
equator, the cool sinks
The cool air starts to warm
and sucks moisture from
ground below.
This is what creates deserts
at 30° N & S latitude.
Same basic process
happens at 60° latitude.
7. Atmospheric Circulation
Prevailing Winds
Winds blow predominantly in
one direction throughout the
year.
Because Earth rotates, these
winds do not blow directly north
or south- instead they are
deflected
Wind patterns in Northern
Hemisphere:
Tradewinds- btwn 0-30° latitude;
blow from the NE
Westerlies- btwn 30-60° latitude;
blow from the SW
Easterlies- btwn 60°-poles; blow
from the NE parts of poles
Air circulation pattern
animation
8. Ocean circulation patterns
Have large effect on
climate because water
holds lots of heat.
Movement of ocean
water caused by
Winds
Earth’s rotation
Moving ocean water
redistributes warm and
cold surface water
Can have an effect on
local coastal climates.
9. El Nino Southern Oscillation
(ENSO)
El Nino
Change in warm & cold
water masses in Pacific
ocean
Pacific winds strengthen and
push warm air & rain toward
southern US & South
America. Makes it drier in
Australia & Indonesia
La Nina
Opposite of El Nino… water
is cooler than normal.
Both can alter fishing
industry in S. America.
El Niño-Southern Oscillation
- YouTube
10. Topography
Height above sea level
influences climate.
Temperatures fall 11°F for
every ½ mile increase in
elevation.
Rain shadow effect
As air moves east toward
Rocky mtns, the height of
the Rockies block the
weather. Rain falls on the
western side of the
mountain making the
eastern side drier.
11. Miscellaneous Influences
Solar Activity
Solar maximum- sun
emits an increased
amount of UV radiation,
warming the surface of
the earth a little
Volcanic Activity
Produce sulfur dioxide
that can react with dust
& water vapor to make
haze that reflects light
and cools global
temperatures
12. What causes our seasonal
changes?
Caused by tilt of
Earth’s axis.
Angle at which the
sun’s rays strike the
Earth changes as
the Earth moves
around the sun.
13. You should be able to:
Explain the difference between weather
and climate.
Name four factors that determine
climate.
Explain why different parts of the Earth
have different climates
Explain what causes the seasons.
