The Reasons for Seasons
Rotation vs.
Revolution
Tilt of the
Earth’s Axis
Equinoxes and
Solstices
Seasons
Misconception
The Seasons
AM and PM
Daylight
Saving Time
•
_____________ is the spin of the Earth around its axis.
– The Earth rotates once a day (______ ____ _________).
• _____________ is the orbit of one object around another.
– The Earth revolves around the Sun ________ ____ _______.
• The _______ around which the Earth rotates is tilted by _____ ___________
• This is what causes seasons.
• _____ _________(__________) ___________ (March) Equal day and night
• The _________ _____________ (June)
Longest day of the year
• The ___________ (________) __________(Sept.) Equal day and night
• The Winter Solstice (December) Shortest day of the year
• Many people think that the ___________ ______ ______ ___ ______
__________ ___ _____ _________ _______ _____ _____. However:
– The Earth’s orbit around the Sun is nearly a perfect circle. The Earth is
slightly closer to the Sun in January and farther from the Sun in July.
– If the seasons were due to our distance from the Sun both
hemispheres would have the same seasons at the same time.
• In fact, the seasons are due to _____ _______ ___ ______ _________
_______. Consider what happens on June 21 when the northern hemisphere
of the Earth is tilted toward the Sun:
• The sunlight strikes the ground more vertically than in ___________. The light
is spread out over less ground and heats the ground better.
• The _______ is above the horizon for a ___________ period of time.
• At midday, the Sun is on your meridian.
– This occurs close to, or at, noon.
– A.M. comes from ante meridiem (_________ ____________)
– P.M. comes from post meridiem (_________ ____________)
• During the late ________, __________, and early _________, we set out clocks
ahead to have an extra _______ of daylight at the end of the day.
– This change in time is called ___________ ____________ ________.
– The idea of changing our clocks was first used in the United States
during World War I to conserve energy.
• Since 1986, the United States has set our clocks one hour ahead on the first
Sunday in April and one hour behind on the last Sunday in October.
– _______ _______, _____ ______.