Lecture One: Solar Radiance

Question 1

What are the three main trace gases responsible for absorption of infrared
solar radiation in the Earth’s atmosphere?

Answer 1

Water, Oxygen, Carbon Dioxide (H20, O2, CO2)

Question 2

What gas in the Earth’s atmosphere absorbs UV radiation?

Answer 2

Ozone

Question 3

How many revolutions does the Earth make as it rotates once around the
sun?

Answer 3

one

Question 4

At what time of the day does the sun have an elevation angle of 0°?

Answer 4

sunrise and sunset

Question 5

At what time of the day does the sun have a maximum altitude angle?

Answer 5

solar noon; when it reaches its highest position in the sky

Question 6

What is the maximum altitude angle of the sun in Karlsruhe on 21st Dec?

Answer 6

Winter solstice (21st of Dec):

α = 90 - φ + δ
α = 90 - 49 + 23.5
α = 17.5 degrees

Question 7

What direction is the sun at solar noon in the southern hemisphere?

Answer 7

directly north in southern hemisphere

(directly south in northern hemisphere)

Question 8

What direction is the sun at sunrise in Karlsruhe on the spring equinox?

Question 9

Why does the sky appear red at sunrise / sunset ?

Answer 9

At sunset, light has further to travel through the atmosphere.

The shorter wavelength blue light is scattered further, as the sunlight passes over a greater distance, and we see the longer wavelength yellow and red light.