3.4.b Reasons for Seasons (Review)

3.4.b Seasons

I can explain what causes seasons

Reasons for Seasons

The main reason for seasons is the tilt of Earth's axis (NOT the distance to the sun). 

The Earth's axis is tilted by 23.5°

Seasons & Hemispheres

- At some parts of the year, the Northern hemisphere is tilted towards the sun, while the Southern hemisphere is tilted away causing different seasons.

- For example, when it is summer in the Northern Hemisphere, it is winter in the Southern Hemisphere (ref. image).

Direct & Indirect Sunlight

• The earth is a sphere, so some parts of the earth receives 'direct sunlight', while other parts receives 'indirect sunlight'.

• Direct sunlight is concentrated over a small area and results in more intense heat, while indirect sunlight is spread over a larger area and is less intense (ref. image).

Solstices

- Solstices occur twice a year, when the tilt of the Earth's axis is oriented directly towards or away from the sun.

- Winter solstice (and the shortest day in the NH): Dec. 21

- Summer solstice (and the longest day in the NH): Jun. 21

Equinoxes

• Equinox literally means "equal night".

• It occurs twice a year, and the Earth's tilt faces neither towards nor away from the sun.

• Both hemispheres receives the same amount of sunlight. Day and night are the same length.

• Spring equinox: March 21

• Fall equinox: Sep. 21

Multiple Choice

What effect does the tilt of the earth have?

• It changes the angle that the sun strikes the earth in different land areas

• When the earth is tilted away from the sun we have night

• It causes the earth to be farther away from the sun at different times of the year

• When the earth is tilted away from the sun we have day

Multiple Choice

Which of the following best describes the tilt of the earth when it is summer in the southern hemisphere?

• The northern hemisphere is tilted toward the sun

• The northern hemisphere is tilted neither toward or away from the sun

• The northern hemisphere is tilted away from the sun

• Neither the northern nor the southern hemisphere is tilted towards the sun.

Multiple Choice

In summer, the axis of the earth is pointed away or toward the sun?

• towards
• up
• down
• away

Multiple Choice

What are the reasons for the seasons?

• Earth's tilt and rotation.
• Earth's rotation and revolution.
• Earth's tilt and revolution.
• Earth's tilt and resolution

Multiple Choice

Which definition explains what a solstice is?

• When the days and nights are equal (12 hours each)

• When the Sun is at its lowest or highest in the sky (longest & shortest days)

• When the Sun moves across the sky

• When we don't see any light for 6 months

Multiple Choice

Why is it warmer in the summer?

• Closer to the sun
• More direct light from Earth's tilt
• Stronger light from the sun
• Earth spins slower

Multiple Choice

Which season is taking place in the Northern Hemisphere in Position 2?

• Winter
• Spring
• Summer
• Fall

Multiple Choice

What is the Earth's tilt in degrees?

• 25.3 degrees

• 32.5 degrees

• 28.5 degrees

• 23.5 degrees

Multiple Choice

What season is letter A?

• Winter
• Summer
• Spring
• Fall