REVIEW The Electromagnetic Spectrum

Figure 2.5

Figure 2.6

Solar and Terrestrial Energy

Figure 2.7

II. Solar Energy: From Earth to Sun

Sun emits:• 8% UV, x-ray, gamma

radiation• 47% visible radiation• 45% infrared wavelengths

Distribution of Insolation

Tropics receive more concentrated insolation due to the Earth’s curvature

Tropics receive 2.5X more than poles

Subsolar point

REVIEW

Lecture 3: The Seasons  

Seasonality  

Reasons for Seasons  

Annual March of the Seasons  

The Tides

SeasonalitySeasonal changes

Sun’s altitude – angle above horizon

Declination – location of the subsolar point

Daylength

The Suns Position

Reasons for Seasons Revolution

Rotation

Tilt of Earth’s axis

Axial parallelism

Sphericity

Reasons for Seasons Revolution

Earth revolves around the Sun

Voyage takes ?

Earth’s speed is 107,280 kmph (66,660 mph)

RotationEarth rotates on its axis once every ? hours

Rotational velocity at equator is 1674 kmph (1041 mph)

Revolution and Rotation

Figure 2.13

Reasons for Seasons Tilt of Earth’s axis

Axis is tilted 23.5° from plane of ecliptic

Axial parallelismAxis maintains alignment during orbit around the Sun

North pole points toward the North Star (Polaris)

Sphericity

Axial Tilt and Parallelism

Figure 2.14

Earth-Sun Relations

Annual March of the SeasonsWinter 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

The Egg and the EquinoxBad Astronomy: Only on the day of the Vernal (spring) Equinox, can you stand a raw egg on its end. Good astronomy: If you can stand a raw egg on end, it has nothing to do with the Equinox.

The TidesWhat are tides? Tides are periodic rises and falls of large bodies of water.

What causes tides?

Gravitational pull of the moon and the sun.

The Tides

The Tides1. Spring Tides 2. Neap Tides

The Tides