Ch 7.6A Is our climate also changing on a local scale?

Question 1

What are the changes in other weather elements because of climate change?

Answer 1

1. Decrease in visibility.
2. Decrease in relative humidity.
3. Increase in cloud cover and rainfall.
4. Decrease in the amount of sunshine received.

Question 2

Explain why there is a change in decrease in visibility.

Answer 2

1. Urban activities such as transport, power plants and manufacturing activities produce air pollutants like nitrogen oxide, sulphur dioxide, carbon dioxide and suspended particles. This causes high concentration of air pollutants which reduce visibility.
2. Low wind speeds in urban areas cannot disperse air pollutants.

Question 3

Explain why there is a decrease in relative humidity.

Answer 3

1. Vegetation is removed for urban development -> Decrease in evapotranspiration.
2. Wet surfaces are reclaimed for urban development -> Decrease in evapotranspiration.

Question 4

Explain why there is an increase in cloud cover and rainfall.

Answer 4

1. Higher air temperature -> Air heats up and rises.
2. Tall building -> Wind rise higher up into the atmosphere. -> Rising air currents.
3. High concentration of suspended particulates -> More condensation nuclei -> Favours formation of cloud.

Question 5

Explain why is there a decrease in the amount of sunshine received.

Answer 5

1. More clouds reflect more solar radiation back into space.
2. High concentration of suspended particles scatter more solar radiation back into the space.

Question 6

What is urban heat island effect?

Answer 6

When urban area that has a mean air temperature higher than the surrounding rural areas.

Question 7

How does busy urban activities causes heat island effect?

Answer 7

1. Produce air pollutants which exert blanket effect and prevent heat from escaping into the space.
2. Produce man-made heat.
3. Produce water vapour which is an excellent absorber of solar energy (it absorbs large amount of heat without a large increase in its own temperature).

Question 8

How does buildings and roads made of concrete and asphalt causes heat island effect?

Answer 8

1. Absorb and store more heat in daytime.
2. The stored heat is released at night.
3. Dark coloured asphalt heats up even more intensely as it absorbs more light than light-coloured object.

Question 9

How does the tall and densely packed buildings cause heat island effect?

Answer 9

Increase the surface roughness
-> Increase the frictional drag on winds.
-> Reduce block wind flow and speed.
-> Heat is trapped.

Question 10

How does removing vegetation and reclaiming wet surfaces for urban development increase heat island effect?

Answer 10

Less evapotranspiration and shading
-> Less cooling effect.

Question 11

Why does more vegetation and wet surface in the rural area can help decrease heat island effect.

Answer 11

More evapotranspiration.
-> More cooling effect.

Question 12

Why does more open space in rural area can help decrease in heat island effect?

Answer 12

More space to release heat.
-> More cooling effect.