Topic 2.2: Greenhouse Effect Questions

The peak of a black body's emission spectrum is measured to be at a wavelength of 4.8 × 10⁻⁷ m.

Using Wien's displacement law (λ_max T = 2.9 × 10⁻³ m K), determine the surface temperature of the body.

Identify which of the following statements about Earth's albedo are correct.

I. Earth's albedo can change with the time of day.
II. Earth's albedo depends on the latitude of the location.
III. Earth's albedo increases when cloud cover increases.

State what is meant by a **greenhouse gas**.

A region on the equator has the Sun directly overhead at midday.

The intensity of solar radiation arriving at the top of the atmosphere is 1360 W m⁻², and the atmosphere has an albedo of 0.30.

Assuming no absorption by the atmosphere, what is the intensity of solar radiation reaching the surface?

The filament of a lamp behaves as a black body.

The lamp is dimmed, so the filament's temperature falls.

State how the shape of the filament's black-body radiation curve changes as a result.

A small heat lamp radiates 120 W of infrared power equally in all directions.

Calculate the intensity of the radiation 4.0 m from the lamp.

Define what is meant by a black body, and outline why a real star is a good approximation to one.

A textbook states that without the greenhouse effect the Earth's average surface temperature would be around −18 °C instead of about 15 °C.

Estimate, in kelvin, how much warmer the greenhouse effect makes the surface, and state what this shows about the greenhouse effect.

Identify **two** greenhouse gases whose atmospheric concentration is increased by human activity, and for each give one human source.

State what is meant by the albedo of a surface.

A satellite measures that a region scatters 4.2 × 10¹⁶ W of solar power back to space out of 1.2 × 10¹⁷ W of incident solar power.

Calculate the albedo of this region.

A geography student researching climate change reads that human activity since the Industrial Revolution has strengthened the natural greenhouse effect, leading to global warming.

Which human activity is the main cause of this enhanced greenhouse effect?

State what is meant by the solar constant.

Describe the difference between the **natural** greenhouse effect and the **enhanced** greenhouse effect.

A region of ocean has an albedo of 0.08.

After it freezes over, the new sea ice has an albedo of 0.60.

The average incoming solar intensity is 340 W m⁻².

Calculate the intensity absorbed before and after freezing, and explain how this acts as a feedback that affects warming.

Outline the mechanism by which greenhouse gases keep the Earth's surface warmer than it would be with no atmosphere.

A spacecraft drifts away from the Sun until it is twice as far from the Sun as the Earth is.

At Earth's distance the intensity of sunlight is the solar constant, 1.36 × 10³ W m⁻².

Determine the intensity of sunlight at the spacecraft, and explain why it is not simply half the solar constant.

On axes of intensity (vertical) against distance from the Sun (horizontal), sketch how the intensity of the Sun's radiation varies with distance, and label one feature that shows the relationship is an inverse-square law.

Sunlight that reaches the Earth's surface is mostly visible radiation, but the radiation the surface emits back out is infrared.

State **why** the surface emits at a longer wavelength than the radiation it receives.

A student writes three statements about the albedo of the Earth.

I. The albedo of a given location can change over the course of a single day.
II. The albedo of a polar ice cap is greater than the albedo of a tropical ocean.
III. Increasing cloud cover over a region tends to increase its albedo.

Which of the statements are correct?