Ch 9.1 What happens when solar radiation reaches the earth?

Question 1

What are the processes that occur when solar radiation enters the atmosphere?

Answer 1

1. Some of the radiation is absorbed by certain materials, which increase in temperature as a result.
2. Some materials allow radiation to penetrate without absorption.
3. Some other objects reflect the radiation back without absorbing or allowing it to pass through.
4. When the reflected radiation travels in different direction, it is called scattering.

Question 2

How is energy transferred from the earth’s surface to the atmosphere? (4 means of heat)

Answer 2

1. Conduction. Heat is transferred through contact, from a hotter object to a cooler one.
2. Convection. Heat is transferred in fluids such as water and air by vertical circulation.
3. Radiation. Heat is transferred to the atmosphere from the earth’s surface through long wave radiation.
4. Evaporation. Latent heat is absorbed and stored in the water vapour when water changes its state from liquid to vapour through evaporation.

Question 3

What is the energy budget of the atmosphere?

Answer 3

Energy refers to the balance between incoming and outgoing energy. When:
incoming energy > outgoing energy (surplus budget)
-> average temperature increases.
outgoing energy > incoming energy (deficit budget) -> average temperature decreases.
incoming energy = outgoing energy (balanced budget) -> average temperature maintained.

Question 4

What are the processes for energy absorbed?

Answer 4

1. Solar radiation absorbed from the sun. (Insolation)
2. Heat transferred from convection and conduction.
3. Heat transferred from the earth’s surface by evaporation.
4. Net long wave radiation from the earth surface.

Question 5

What is the process of energy released?

Answer 5

Long wave radiation from the atmosphere to the space.

Question 6

What are the factors affect the amount of insolation received on the earth’s surface?

Answer 6

1. Angle of the sun.
   -> Latitude.
   -> Time of day.
   -> Season.
2. Duration of daylight.
3. Atmosphere.
4. Albedo.

Question 7

Elaborate on angle of the sun as one of the factors affecting the amount of insolation received.

Answer 7

1. When the sun is directly over head, or when the angle of the sun is 90 degrees, it is known as the overhead sun.
2. The larger the angle of the sun, the more concentrated and the more intense the insolation.
3. The angle of the sun varies with latitude, time of day and season.

Question 8

Elaborate on latitude as under angle of the sun one of the factors affecting the amount of insolation received.

Answer 8

1. The angle of the sun is larger in low-latitude regions than in high latitude regions.
2. The same amount of insolation is concentrated on a smaller area in low-latitude regions.
3. Intensity of the insolation received decrease with increasing latitude.

Question 9

Elaborate on time of day as under angle of the sun one of the factors affecting the amount of insolation received.

Answer 9

1. The angle of the sun increases from sunrise, reaches maximum at noon and decreases to the lowest point at sunset.
2. Insolation is the most intense at noon.

Question 10

Elaborate on season as under angle of the sun one of the factors affecting the amount of insolation received.

Answer 10

1. At the summer solstice, the Northern Hemisphere is tilted towards the sun. The overhead sun is located at the Tropic of Cancer. Places in the Northern Hemisphere experience a larger angle of sun and a longer duration of sunlight. As a result, more insolation is received in the Northern Hemisphere. Areas north of the Arctic Circle receive 24 hours of daylight.
2. At winter solstice, the pattern is reversed. The overhead sun is located at the Tropic of Capicorn. Areas north of the Arctic Circle receive 0 hours of sunlight.
3. At the spring equinox and the autumnal equinox, the overhead sun is at the Equator. Both hemispheres receive roughly equal amounts of insolation.

Question 11

Elaborate on duration of sunlight as one of the factors affecting the amount of insolation received.

Answer 11

1. In general, the larger the duration of daylight, the more the insolation received.
2. There are 12 hours of daylight at the Equator throughout the year. The annual variation of insolation increases with increasing latitude.
3. Although the total duration of daylight at different latitudes varies with these years, the total duration of daylight in a year is the same at all latitudes.

Question 12

Elaborate on the atmosphere as one of the factors affecting the amount of insolation received.

Answer 12

1. Dust particles, gas molecules and clouds in the atmosphere reflect, absorb or scatter solar radiation.
2. At higher latitudes, the sun’s rays have to travel a longer distance through the atmosphere. This results in a greater loss of insolation.
3. At the equator, the sun’s rays travel a shorter distance through the atmosphere. This results in a smaller loss of insolation.
4. However, the amount of cloud cover at the Equator is large, reducing the amount of insolation reaching the earth’s surface.
5. The greatest amount of insolation is at around 23.5 N and 23.5S where there is less cloud cover.

Question 13

Elaborate on albedo as one of the factors affecting the amount of insolation received.

Answer 13

1. The degree of reflection of a surface, known as the albedo, affects the the amount of insolation being reflected.
2. Albedo can have a major effect on a local scale.
3. The lighter the colour of the earth’s surface, the higher the albedo, the lower the amount of the insolation absorbed by the earth’s surface.