The Reason for the The Reason for the SeasonsSeasons

______________________ Earth Earth ______________ on on ________ ________

(imaginary line through center of (imaginary line through center of Earth from North to South Pole)Earth from North to South Pole)

Rotation is Rotation is ___________ ___________ clockwise clockwise as seen from North Poleas seen from North Pole

Earth spins on its axis like a topEarth spins on its axis like a top

__________ - Axis__________ - Axis Earth Earth tilttilt =_________ =_________

Axis currently Axis currently pointed at Polaris pointed at Polaris (the North Star)(the North Star)

Polaris

______________________ Earth rotates once Earth rotates once

every _______ hrsevery _______ hrs

The rotation causes The rotation causes _______ & ________________ & _________

Earth’s rotation Earth’s rotation causes celestial causes celestial objects to appear to objects to appear to move from east to move from east to west in Northern west in Northern Hemisphere Hemisphere

Night and Day MapNight and Day Map

Just Checking…Just Checking…

What does it mean when we say the What does it mean when we say the Earth rotates? ___________________Earth rotates? ___________________

______________________________________________________________ How would you define or explain How would you define or explain

the concept of Earth’s axis? the concept of Earth’s axis? ________________________

________________________________________________________________

________________________________________________________________

______________________________ Movement of one object Movement of one object aroundaround another another Earth _____________ around SunEarth _____________ around Sun

______________________________ ______________________________ Earth’s orbit is almost Earth’s orbit is almost circular rather circular rather

than oval shapedthan oval shaped but but is still referred is still referred to as anto as an _________________________ _________________________ orbitorbit

________days to revolve once________days to revolve once around around the Sun (~ a year)the Sun (~ a year)

The imaginary line that runs The imaginary line that runs through the north and south through the north and south poles of the Earth is called the poles of the Earth is called the ____________________________________

Decide weather each example is ofDecide weather each example is ofA. Rotation or B. RevolutionA. Rotation or B. Revolution

The Earth spinning on it’s axis. ________________The Earth spinning on it’s axis. ________________ A baseball player running around the infield. A baseball player running around the infield.

________________________ Takes 1 year ________________Takes 1 year ________________ A top spinning ________________A top spinning ________________ Causes day and night. ________________Causes day and night. ________________ Takes 24 hours ________________Takes 24 hours ________________ The moon circling the Earth ________________The moon circling the Earth ________________

Location and Distance in Location and Distance in OrbitOrbit

http://www.uwm.edu/~kahl/CoVis/Seasons/Handout available at

1. The ____________ of the earth

2. The __________ of Sunlight hitting the earth

Two Primary Reasons for the Two Primary Reasons for the Seasons (on Earth)Seasons (on Earth)

SeasonsSeasons

SeasonsSeasons Northern hemisphere tilts _________ Northern hemisphere tilts _________

Sun = warmer (Summer)Sun = warmer (Summer)

SeasonsSeasons Northern hemisphere tilts _________ Northern hemisphere tilts _________

from Sun = cooler (winter)from Sun = cooler (winter)

SeasonsSeasons In the Spring and the Fall, the tilt of the In the Spring and the Fall, the tilt of the

Earth is such that the spread of sunlight Earth is such that the spread of sunlight shines on the Earth approximately ______shines on the Earth approximately ______

SeasonsSeasons

Southern hemisphere seasons are Southern hemisphere seasons are opposite Northern hemisphere opposite Northern hemisphere seasonsseasons

If its Winter here, then Australia is If its Winter here, then Australia is having ____________.having ____________.

SolsticesSolstices Occur twice yearly when the Occur twice yearly when the

Sun is directly over “Tropics” Sun is directly over “Tropics” (23.5(23.5°N and 23.5°S Latitude)°N and 23.5°S Latitude) winter solstice = shortest winter solstice = shortest

day of the year for day of the year for Northern Hemisphere (Sun Northern Hemisphere (Sun directly over Tropic of directly over Tropic of Capricorn-Capricorn-23.5°S23.5°S-at noon)-at noon)

Summer Solstice is the Summer Solstice is the longest day of the year in longest day of the year in the Northern Hemisphere the Northern Hemisphere

(Sun directly over Tropic (Sun directly over Tropic of Cancer-23.5of Cancer-23.5°N°N-at noon-at noon

EquinoxEquinox equal night & dayequal night & day Occurs Occurs twicetwice each each

yearyear Half-way between Half-way between

solsticessolstices noon sun directly noon sun directly

over equator over equator Sun will be at its Sun will be at its

highest point in highest point in our sky at noon our sky at noon but never directly but never directly overhead in overhead in Texas… why do Texas… why do you think this is you think this is true?true?

Your answer should refer to Godley, Your answer should refer to Godley, TX.TX.

This occurs because the Earth’s axis is This occurs because the Earth’s axis is tilted as it moves around the sun. tilted as it moves around the sun. ____________________________

This occurs when the Northern This occurs when the Northern hemisphere is tilted towards the sun. hemisphere is tilted towards the sun. ________________________________

This is when the length of day and night This is when the length of day and night are equal. __________are equal. __________

The shortest and longest days of the The shortest and longest days of the year when the noon sun is directly year when the noon sun is directly overhead at 23.5 degrees. ___________overhead at 23.5 degrees. ___________

This occurs when the Northern This occurs when the Northern hemisphere is tilted away from the sun. hemisphere is tilted away from the sun. ______________________

A.A. WinterWinter

B.B. SummerSummer

C.C. SolsticeSolstice

D.D. EquinoxEquinox

E.E. All of the All of the aboveabove