Transcript What are 2 motions of the Earth?

Aim: What is evidence of the 2
motions of the Earth?
Do Now: What are 2 motions of the Earth?
Homework: Study for Midterm
January 28, 2008
What are the
two motions
of the earth?
How long
does it take
the earth to
rotate?
Rotation & Revolution
24 hours (one day) to
rotate (spin) once on its
axis
How long does 365 ¼ Days (one year) to
complete one revolution
it take the
earth to revolve around the sun
around the
sun?
What does the
earth’s rotation
cause?
Day & Night
As the earth rotates (counter-clockwise), part of
it faces the sun and the rest of it faces away from
the sun and is in darkness.
Why does the
length of the day
change
throughout the
year?
Due to the tilt of the earth’s
axis (23.5° angle)
Example: When the
North Pole is tilted toward
the sun, the Northern
Hemisphere has longer
days and shorter nights
= SUMMER
Where does the
north pole of the
earth always
point?
Towards Polaris
(A.K.A. The North Star)
Where does
the sun and
moon appear
to rise and set?
•The sun, moon, & stars all
appear to rise in the East and
set in the West
•Due to the counter-clockwise
rotation of the Earth
How does the rotation of the earth affect the
motion of the winds & ocean currents?
Northern Hemisphere:
Southern Hemisphere:
The Earth rotates
Counterclockwise
The Earth rotates
Clockwise.
Causing: winds and
ocean currents to be
deflected to the Right.
Causing: winds and
ocean currents to be
deflected to the Left.
What is the deflection
(of winds & water) at
Earth’s surface called?
Observe an animation of the Coriolis effect over Earth's
surface.
The Coriolis Effect.
Yahoo! Video Detail for
coriolis.avi
What evidence 1) Coriolis Effect
shows that the 2) Satellite Pictures
earth rotates?
3) Pictures from the earth
of the night sky would show
arcs of light, or star trails,
from the motions of the
earth.
What evidence 1) Constellations (patterns
shows that the of stars) appear to move
earth revolves Observing the Sky: Motion of the Sun and
Stars - The Night Sky
around the
2) The Sun appears to be larger
sun?
during the winter months and
smaller as summer approaches.
• Perihelion – earth closest to the
sun
•Aphelion – earth furthest away
from the sun
LET’S REVIEW…
• Why do we have day and night on earth?
• If the earth’s axis was not tilted every where
on earth would have how many hours of
daylight and darkness?
• Why does the sun appear to rise in the east
and set in the west?
• What would happen if the earth did not
rotate?
Summary…
• What is the Coriolis Effect?
• How do we know that the Earth
rotates?
• Which motion of the earth causes day
and night?
• How do we know the earth revolves
around the sun?
Aim: Why do we have seasons?
Do Now: How does the rotation of
the earth affect winds in
the Northern Hemisphere?
Homework: Big 8 Review Book
pgs 57-64 & Review Sheet
(Study for next Friday’s Midterm) 2/2
What causes
summer?
The hemisphere that is
tilted toward the sun gets:
1. more hours of sunlight
&
2. more direct sun
The combination of more direct
sunlight & longer days causes the
Earth’s surface and atmosphere to
receive more heat from the sun.
Summer and winter are not affected
by the Earth’s distance from the sun.
Which day of the
year gives us
the most
sunlight?
Summer:
a) Begins in the Northern
Hemisphere on June 21
b) Called the Summer
Solstice “Sun Stop”
c) The most sunlight is
received on this day
d) Length of daylight varies
depending on your distance
from the equator
Which day of the Winter:
year is the
a) Begins in the Northern
shortest?
Hemisphere on Dec 21st
b) Called the Winter Solstice
c) The day of the year when
the Northern Hemisphere
gets the least amount of
sunlight
What is an a) 2 days of the year the sun
shines directly overhead on
equinox?
the equator:
Spring equinox is March, 21st
&
Fall equinox is September,
23rd
b) During this time all places on
earth have 12 hours of
daylight and 12 hours of
darkness.
If it is summer
in the northern
hemisphere,
what season is
it in the
southern
hemisphere?
The Northern and
Southern hemispheres
have opposite seasons.
Earth: What causes the
Seasons?
SUMMARY
• During the year when is the earth closer to the
sun?
• Why do we have seasons on earth?
• If the North Pole is having summer, what
season is the South Pole having?
Aim: How can we explain
time zones on Earth?
Do Now: What causes
the seasons on earth?
Homework:
Handout (17-4)
What are the
time zones?
The earth is divided into
24 time zones
(called standard time)
WHY 24?
USA has 4 time zones:
1.
EASTERN STANDARD TIME
2. CENTRAL STANDARD TIME
3. MOUNTAIN STANDARD TIME
4. PACIFIC STANDARD TIME
As you move west the time in each zone is
one hour earlier than in the previous zone.
What is the
international
date line?
The boundary formed where
the 1st and 24th time zones
meet
What happens when you cross
the International Date Line?
How could you travel back in
time?
Pacific
7 pm
Mountain Central
8 pm
9 pm
Eastern
10 pm
Practice Problem
You board a 6 PM flight from New York’s
JFK Airport headed to Los Angeles’ LAX
in California. The expected flight time is
5 hours. Predict the time your plane will
land and explain why you chose that time.
Why are some time zones
crooked?
Time Zones
NASA Math News
Summary
• Why do we have 24 time zones?
• What happens when you cross the
International Date Line?
• How could you travel back in time?
• Why are some time zones crooked?
• In your own words, explain what time
zones are.