Topic 2.2: Greenhouse Effect Questions

State what is meant by the albedo of a 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.

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

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?

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.

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 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.

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

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 the solar constant.

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.

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

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.

As a metal bar is heated in a furnace it first glows dull red, then orange, and eventually bright white.

Using the laws of black-body radiation, explain why both the colour and the brightness of the bar change as its temperature rises.

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.

Mercury orbits the Sun at a mean distance of 5.8 × 10¹⁰ m, while the Earth orbits at 1.5 × 10¹¹ m where the intensity is the solar constant, 1.36 × 10³ W m⁻².

Determine the intensity of solar radiation at Mercury's distance.

Two stars, X and Y, behave as black-body spheres and emit exactly the same total power.

Star X has surface temperature T and radius 8.0 × 10⁸ m.

Star Y has surface temperature 2T.

What is the radius of star Y?

A household needs a continuous electrical supply of 2.4 kW from solar panels.

The panels are 20% efficient and the sunlight reaching them has an intensity of 8.0 × 10² W m⁻².

Calculate the total panel area required.

The solar constant is S = 1.36 × 10³ W m⁻² and the Earth orbits the Sun at a mean distance d = 1.5 × 10¹¹ m.

Show that the total power radiated by the Sun is approximately 4 × 10²⁶ W.