do now copy down your learning target on page what do you think causes seasons?
TRANSCRIPT
Brain POP: Solstice and Equinox
http://www.brainpop.com/science/earthsystem/solsticeandequinox/
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Words to know:Axis - imaginary line around which
Earth spins, causing day and night, and that is drawn from the
north geographic pole through
Earth to the south geographic pole
http://vortex.plymouth.edu/sun/axis.gif
Words to know:
Rotation - spinning of Earth on its axis, which causes day and night; it takes 24 hours for Earth to complete one
rotationhttp://vortex.plymouth.edu/sun/rot8_an.gif
Words to know:
Revolution - the motion of Earth around the Sun, which takes about 365 1/4
days, or one year, to complete
http://www.usoe.k12.ut.us
Words to know:
Orbit - curved path followed by Earth as it moves around the Sun
http://www.vt-2004.org/mt-2003/mt-mercury-orbit.jpg
The Earth’s Tilt
The Earth's axis is tilted by 23.45°
http://www.crh.noaa.gov/fsd/astro/season.htm
This means that, during part of the year, the northern part of
the Earth will lean more directly to the sun, and during
other parts of the year the southern part of the Earth will.
The northern half faces the
sun for a while, then
moves south of the
equator, only to move back to the north
again.
When the northern hemisphere is leaning away from the sun, the rays
coming from it hit this part of the Earth at a smaller angle than on
other parts of the world.
This means that the same amount of light is distributed over a larger
surface, and so these places receive less heat than the others.
In half a year, the situation reverses, and it is now Winter in the southern hemisphere since that part of the
earth is now leaning away from the sun.
The energy that hits the Earth by the Sun changes over of the year.
The angle the Sun is above the horizon determines how much heat and light strike each
square meter of ground.
http://inkido.indiana.edu/a100/celestialsphere5.html
In the winter the Sun's energy is weakened because the Sun's ray strike the ground rather indirectly as compared to the summer months when the Sun's rays strike the ground more
directly.
http://inkido.indiana.edu/a100/celestialsphere5.html
This means that the ground receives more energy (more heat) per square
meter in the summer than in the winter.
More energy is received by the ground during the summer (high
temperatures) and less energy during the winter (lower temperatures).
http://inkido.indiana.edu/a100/celestialsphere5.html
So, seasons are caused the So, seasons are caused the tilt of the Earth’s axistilt of the Earth’s axis
Remember:
• The seasons are the result of this tilt of the Earth's axis.
• If the tilt of the Earth's axis was 0° there would be no difference in how the rays from the sun hit its different regions, and there would be no seasons.
The Earth's seasons are not caused by the differences in the
distance from the Sun throughout the year.
The seasons are the result of The seasons are the result of the tilt of the Earth's axis.the tilt of the Earth's axis.
I know this is a repeat, but it is important that you understand this idea. Many
Americans, including Harvard graduates, do not know what causes seasons!
http://www.nmm.ac.uk/uploads/gif/seasons-full.gif
Discuss as a classLook closely at where the Sun is hitting the Earth during each season. What characteristics do you observe during each season?
Seasons Diagram, p.
• Write a description and shade in the Earth as you learn about each season.
o The solstices mark the points at which the poles are tilted at their maximum toward or away from the sun.
o The equinoxes occur when the Earth is between solstices, it is spring and fall
o Day and night have almost same (equal) duration all over the planet
Summer SolsticeJune 20 or 21
• N. hemisphere tilted toward the Sun– Sun at highest point (over Tropic of Cancer)– Longest day
• North Pole
(24 hrs sunlight)• South Pole
(24 hrs darkness)
Autumnal EquinoxSeptember 22 or 23
• N hemisphere is tilted neither towards nor away from the Sun– About 12 hours
of sunlight
Winter SolsticeDecember 21 or 22
• N hemisphere is tilted away from the Sun– Sun at lowest point (over Tropic of Capricorn)– Shortest Day
• South Pole
(24 hrs sunlight)• North Pole
(24 hrs darkness)
Vernal (Spring) EquinoxMarch 20 or 21
• N hemisphere is tilted neither towards nor away from the Sun– About 12 hours of sunlight
Summary• Underneath your diagram, write 2-3
sentences summarizing the reason for seasons on Earth.
• Share out!
SummerSolstice
Vernal Equinox
Autumnal Equinox
WinterSolstice