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Earth’s Tilt and Seasons
Earth’s Tilt and
Seasons
Axis:
imaginary line that passes through Earth’s
center and the North & South Poles
Earth’s axis tilt = 23.5°
• causes Earth’s seasons
• causes ‘length’ of day to change throughout the year
Rotation:
Earth’s spinning on its axis
• causes night & day
• Earth rotates every 24 hours
Revolution:
movement of one object around another
• Earth revolves around the sun
every 365.25 days
Orbit:
an object’s path as it revolves around another object
• Earth’s orbit around the sun is slightly
elliptical, not perfectly circular
• When we are tilted toward the sun, we have summer.
• When we are tilted away from the
sun, we have winter
Equator: imaginary line encircling the Earth like a belt at 0° latitude
• All lines of latitude are measured as north or south of the equator.
Label your map!
Tropic of Cancer: latitude 23.5° N
Tropic of Capricorn: latitude 23.5°S
Label your map!
Arctic Circle: latitude 66.5° N
Antarctic Circle: latitude 66.5°S
Label your map!
Solstice: 2 days of the year when the noon sun is directly overhead at either 23.5° S or 23.5° N
1. Summer: longest “day” of year (daylight)
Around June 21st
2. Winter: shortest “day” of year
(daylight)
Around Dec. 21st
Equinox: 2 days of the year when the noon sun is directly overhead at the equator (equal amt. of day & night)
1.Vernal (spring)
Around March 21st
2.Autumnal (fall)
Around Sept. 21st
Seasons simulator
Copy this diagram into your notes.
What season is it at your house in this animation?
Climate
Global Wind
Patterns
&
Weather:
current condition of Earth’s
atmosphere at a particular
time & specific place
Climate:
average weather over a long
period of time (decades/centuries)
“Climate is what you expect, weather is what you get.”
• Because sun’s rays strike
earth at different angles,
we have unequal heating
of the earth’s surface
Two factors that influence climate
1. Temperature
2. Precipitation
4 Factors influencing a climate’s
TEMPERATURES
1. Latitude
2.Altitude
3.Distance from water
4. Ocean currents
1. Latitude:
distance on a map measured
north & south of the equator in degrees
Polar
Polar
GAH! The spelling on this illustration is terrible. Stupid internet!
Label your map!
3 BASIC CLIMATE ZONES
A. Tropical zone = HOT
• near equator
b/t Tropic of Cancer (23.5°N)
and
Tropic of Capricorn (23.5°S)
Label your map!
B. Temperate zones (2 )
have seasons, not always hot or
cold
b/t Tropic of Cancer (23.5°N)
and
Arctic Circle (66.5°N)
AND
b/t Tropic of Capricorn (23.5°S)
and
Antarctic Circle (66.5°S)
Label your map!
C. Polar zones (2) = COLD
b/t Arctic Circle (66.5°N)
and
North Pole (90°N)
AND
b/t Antarctic Circle (66.5°S)
and
South Pole (90°S)
Label your map!
2. altitude:
distance above earth’s surface; measured from sea level
higher altitudes = cooler temps.
Mt. Kilimanjaro latitude = 3°S
3. distance from LARGE bodies of
H2O (oceans or inland seas)
closer to H2O = more moderate
climate
4. ocean currents:
flow of water in a particular
direction in the ocean
• warm currents carry warm H2O;
• cold currents carry cold H2O
Gulf Stream: warm H2O ocean
current starts at tip of Florida and warms eastern U.S. &
western Europe
Copy this diagram to show windward
(wet) & leeward (dry) sides of
mountain
H2O
desert
2. prevailing winds:
winds that blow in one
general direction
Aerosols in the atmosphere
(video)
a. Trade winds • flow toward equator from about 30°N
& 30°S latitude
• blow from the east to the west
• can bring storms like hurricanes across
the ocean from Africa to the U.S.
• used by trading ships to quickly get
across the ocean from Europe to the
New World
60°N
60°S
30°S
30°N
0°
Label your map!
b. Westerlies
• blow between 30 ° and 60 ° latitude
in both the N and S hemispheres
• move from west to east
• move weather across the U.S. and
Canada
60°N
60°S
30°S
30°N
0°
http://www.ssec.wisc.edu/data/us_comp/m
ovie-large.php
c. Polar Easterlies
• Dry and extremely cold air from
the poles
• Flow between the poles and the
Westerlies, in both N and S
hemispheres.
• Blow from east to west
60°N
60°S
30°S
30°N
0°
Label your map!
60°N
60°S
30°S
30°N
0°
The Coriolis Effect • caused by earth's rotation, currents
seem to:
o turn clockwise in the Northern
Hemisphere
o turn counterclockwise in the
Southern Hemisphere.
• influences the direction of winds &
ocean currents around the world
Label your map!
Weather you like it or not! (4m)
National Geographic.com Weather 101
Weather: condition of the atmosphere at a
particular time and place
Meteorology: the study of weather
Meteorologist:
scientist who
studies the
weather
AND
tries to predict it
All weather systems are powered by
the SUN
Air: consists of different gases, including H2O vapor, and other particles • it has mass & volume and exerts pressure
•denser air has more pressure
5 Factors that affect weather:
1. humidity 2. cloud cover 3. temperature (heat)
4. air pressure 5. wind
(spells “watch” backwards)
1. Humidity: amount of water vapor in the air
• condenses into clouds which can
result in precipitation
• Warm air holds more water vapor than cold air, so it’s more humid in the summertime!
dew point:
temp. at which condensation occurs (both in the air or on the ground)
hygrometer: instrument used to measure relative humidity
2. Clouds form when H2O vapor cools
and condenses onto tiny particles in the air
3. Temperature measurement of amount of thermal
energy
affects weather by affecting:
1. air pressure
2. winds
3. humidity
thermometer: instrument used to measure
temperature
4. Air pressure: the force exerted by a
column of air pushing down on an
area
affected by
• altitude
•higher atmosphere is thinner/less
dense*
• temperature
•warmer air expands and is less
dense *“ear popping” is caused by unequal air pressure
Normal air pressure (at sea level): 14.7 psi
Barometer: instrument used to
measure air pressure
5. Wind: movement of air from an
area of high pressure to an area of low
pressure
WINDS ARE CAUSED BY DIFFERENCES IN AIR PRESSURE
Anemometer: instrument used to measure wind speed
Wind vane: instrument to show wind direction
Wind map
Air mass: a huge body of air with similar:
• humidity (moisture content)
• temperature
• air mass properties depend on where on Earth it develops.
AIR MASSES
• Changes in weather are caused
by the development and
movement of large air masses.
Maritime (m)
• starts over water
• brings in moist air
Continental (c)
• starts over land
• brings in dry air
Tropical (T)
• starts near the equator
• brings in warm air
Polar (P)
• starts in polar regions
• brings in cold air
AIR MASS GLOBE MAP
4 Types of Air Masses
1. Maritime tropical (mT)
2. Maritime polar (mP)
3. Continental tropical (cT)
4. Continental polar (cP)
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1. Maritime
2. Continental
1. Tropical
2. Polar
Jet stream
• develops where air masses of
drastically differing temperatures
meet. • VERY strong current (stream) of winds
high up in the atmosphere
Pilots use them when
flying from west to
east to decrease
travel time.
Front:
boundary where
• air masses meet , but
• do not mix Type depends on
• kinds of the air masses, and • how they move.
3 basic types of fronts: 1. warm
2. cold
3. stationary
Hyperlink: weather fronts (4:44m)
The direction the symbol is pointing
is the direction it is GOING!
1. warm front • warm air mass pushes into a slowly
moving cold air mass.
• cold air is denser, so warm air is pushed up.
• can cause precipitation for days
Warm Front
2. cold front • fast moving cold air mass runs
into a slower warm air mass • denser cold air slides under less dense warm
air.
• associated with violent storms
Cold Front
3. Stationary front • cold and warm air masses
meet, but neither mass moves
the other.
• the two air masses face each other in a “standoff.”
Weather Map #1
Weather Map #2
Tropical Weather
3 types based on wind speed
1. Tropical depression
• storm with max. sustained winds of
38 mph
• forms over warm tropical oceans
• storm is numbered
2. Tropical storm
• storm with max. sustained winds
between 39 – 73 mph
• storm is named
• forms from a tropical depression
3. Hurricane
• Largest storm on Earth
• forms from a tropical storm
• Sustained wind speeds of at least 74
mph
• counter-clockwise winds
• categorized from Category 1 (74-95
mph) to Category 5 (over 155 mph)
Hurricanes • Warm temperatures fuel them.
• Cool temperatures slow them down.
• Prevailing winds push them in different directions.
Tracking Map
FRONT SYMBOLS
