Describe how albedo affects the Earth’s surface temperature and its climate. Class 9

Describe how albedo affects the Earth’s surface temperature and its climate. Class 9

Question 1.

Describe how albedo affects the Earth’s surface temperature and its climate. Class 9

Answer:

The fraction of solar radiation reflected by a surface is called its albedo. The word comes from Latin meaning “whiteness.” 

How albedo affects surface temperature:

(a) High Albedo Surfaces:

1. Surfaces like snow and ice have very high albedo (0.80 - 0.90).
2. They reflect a large proportion of incoming solar radiation back into space.
3. As a result, they absorb very little heat and remain cool.
4. This is why polar regions are extremely cold — the snow and ice keep reflecting sunlight rather than absorbing it.

(b) Low Albedo Surfaces:

1. Surfaces like black soil and ocean water have lower albedo.
2. They absorb more solar radiation and heat up more quickly.
3. This makes such regions relatively warmer.

How Albedo Affects Climate:

(a) Polar Regions:

1. High albedo of snow and ice keeps polar regions very cold, maintaining the cryosphere.
2. If ice melts due to global warming, albedo decreases, causing more heat absorption — further accelerating warming. This is called the ice-albedo feedback loop.

(b) Urban Areas:

1. Cities have dark roads (asphalt) and concrete buildings with low albedo.
2. They absorb more solar radiation and re-radiate heat, making cities warmer than surrounding rural areas.
3. This is known as the Urban Heat Island Effect.

(c) Forests vs Deserts:

1. Dark green forests have lower albedo and absorb more heat.
2. Light coloured deserts and sandy areas have higher albedo and reflect more sunlight.

Albedo table from the chapter:

Conclusion: Albedo plays a crucial role in determining how much solar energy a region absorbs or reflects. High albedo keeps regions cool while low albedo makes them warmer, directly influencing local and global climate patterns.