THE SEASONS

WHAT DO YOU KNOW? In small groups, answer the following questions on large chart paper… –What are the names of our seasons? –Why do we have 4 seasons in Canada? –When do the seasons change? Why then? –What is the typical weather like during the 4 seasons? Why? –How are the seasons different in other parts of the world?

DEMONSTRATION Step1: Form a large “circle” around the front section of desks Step2: Pass the globe around the circle, while keep it upright and pointed the same direction Step3: Discuss

WHAT’S GOING ON? Earth’s Seasons result from the 23.5° tilt of the Earth’s axis

WHAT’S GOING ON?

The tilt results in portions of the Earth’s surface receiving higher and lower amounts of direct sunlight during the year.

Summer When the Northern Hemisphere is pointing towards the Sun it receives more direct sunlight and experiences Summer This is Winter in the Southern Hemisphere

Summer Summer begins when the Sun appears to reach its highest point in the sky. Longest Day. Summer Solstice: ~June 21st

Summer During our summer, the Sun never sets near the North Pole

Winter When the Northern Hemisphere is pointing away from the Sun it receives less direct sunlight and experiences Winter This is Summer in the Southern Hemisphere

Winter Winter begins when the Sun appears to reach its lowest point in the sky. Shortest Day. Winter Solstice: ~December 21st

Winter During our winter, the Sun never sets near the South Pole

Spring/Fall When the axis tilt is side-on to the Sun, the Northern and Southern Hemispheres receive relatively equal quantities of direct sunlight.

Spring/Fall An Equinox occurs when the Sun appears to cross the Celestial Equator. Autumnal (Fall) Equinox: ~Sept 21st Vernal Equinox: ~March 21st

Equator Equatorial region = region from Tropic of Cancer (23° North of Equator) to Tropic of Capricorn (23° South of Equator)

Equator Equatorial region is the only portion of Earth where the Sun can ever be directly overhead

Equator The Equatorial Region always receives large quantities of direct sunlight!

Equator Only 2 seasons: Rainy and Dry Based on position of the “Rain belt”

WRAP-UP QUESTIONS 1.What would happen to the Earth’s seasons if the its orbit was perfectly circular? 2.What would happen to the seasons if the Earth was straight up and down (not tilted by 23.5°)? 3.What would happen to the seasons if the Earth was tilted onto its side (like Uranus)? 4.Why do the polar regions experience 4 seasons while the equatorial regions experience 2? 5.Why do the poles experience 6months of light and 6 months of dark?