Seasons

Earth's changing seasons : Earth's changing seasons Winter Spring Summer Autumn

Revolution and Rotation : Revolution and Rotation Figure 2.13

Slide 3 : Earth's shape:- Oblate Spheroid Earth - Sun mean distance:- 150,000,000 km (93,000,000 mi)

Slide 4 :

Slide 5 : Perihelion – closest at January 3 147.2 million km (91.5 million miles) Aphelion – farthest at July 4 152.0 million km (94.5 million miles)

Annual March of the Seasons : Annual March of the Seasons Figure 2.15

Slide 7 :

Slide 8 : Figure 2.9

Latitudinal Heat Balance : Latitudinal Heat Balance

Subsolar point and Solar declination : Subsolar point and Solar declination Subsolar point is the place where sun is directly overhead, or where sun’s rays fall perpendicularly. The Sun’s declination is the latitude of the subsolar point.

Slide 11 : The Analemma

Slide 12 : Tropics receive more concentrated insolation due to the Earth’s curvature Tropics receive 2.5X more than poles

Variation in solar radiation : Variation in solar radiation Changes across latitudes and over time Caused by the fact that earth is a “sphere” that is also tilted.

Annual March of the Seasons : Annual March of the Seasons Winter solstice – December 21 or 22 Subsolar point Tropic of Capricorn Spring equinox – March 20 or 21 Subsolar point Equator Summer solstice – June 20 or 21 Subsolar point Tropic of Cancer Fall equinox – September 22 or 23 Subsolar point Equator

Slide 15 :

Slide 16 : Solstices are times when the Sun’s declination is at its position farthest north (Tropic of Cancer) or south (Tropic of Capricorn)

Annual March of the Seasons : Annual March of the Seasons Figure 2.15

Slide 18 : Solstices are times when the Sun’s declination is at its position farthest north (Tropic of Cancer) or south (Tropic of Capricorn)

: Rotation Earth rotates on its axis once every 24 hours Rotational velocity at equator is 1674 kmph (1041 mph) Revolution Earth revolves around the Sun Voyage takes one year Earth’s speed is 107,280 kmph (66,660 mph)

: Tilt of Earth’s axis Axis is tilted 23.5° from plane of ecliptic Axial parallelism Axis maintains alignment during orbit around the Sun North pole points toward the North Star (Polaris) Sphericity

Reasons for Seasons : Reasons for Seasons Revolution Rotation Tilt of Earth’s axis Axial parallelism Sphericity