The heat budget of the earth

The correct answer is A. In the 100-unit heat-budget model, clouds reflect 27 units of incoming solar energy back to space. This shows that clouds reflect a substantial share of the incoming energy.

The correct answer is A. In this model, clouds reflect 27 units while Earth's surface reflects 2, so surface reflection is less than cloud reflection. The surface's reflection is small, but it is not zero.

The correct answer is A. In the heat-budget model, energy scattered or reflected by the atmosphere is redirected rather than reaching the surface, so the amount of incoming solar radiation at the surface is reduced.

The correct answer is A. The heated surface transfers energy upward through terrestrial longwave radiation, sensible heat transfer, and latent heat carried by water vapour. These pathways help return surface energy to the atmosphere and, ultimately, space.

The correct answer is A. In the standard heat-budget model, some outgoing terrestrial longwave radiation passes through parts of the atmosphere that absorb little of it and escapes directly to space; this is called the atmospheric window.

The correct answer is A. With greater absorption and unchanged emission, more energy enters the surface budget than leaves it. This creates a net energy gain and a warming tendency, although it does not by itself specify how quickly temperature will change.

The correct answer is A. Clouds absorb some longwave radiation emitted by the surface and re-emit part of it downward. With fewer clouds, less longwave radiation is returned toward the surface, so the surface-atmosphere system can lose heat more readily to space. The atmosphere does not disappear, and the surface continues to emit radiation at night.

The correct answer is A. During the day, clouds reflect some incoming sunlight and can limit surface heating. At night, they absorb and re-emit some of the longwave radiation leaving Earth, slowing heat loss. Together, these effects can reduce the difference between daytime and nighttime temperatures.

The correct answer is A. Albedo is the fraction of incoming solar radiation reflected by a surface. When albedo decreases, less sunlight is reflected and more is absorbed. If other parts of the radiation balance are unchanged, this can increase net radiation.

The correct answer is A. Snow reflects much of the sunlight. When snow cover shrinks, darker ground or water is exposed and absorbs more energy. This can increase warming and melt more snow, reinforcing the original change; that is positive feedback.

The correct answer is A. The atmospheric window is a range of wavelengths through which some outgoing longwave radiation can escape to space. If it closes, less of this energy escapes directly, so more may be retained in the atmosphere.

The correct answer is A. Many paved surfaces absorb solar energy and store heat, which they can release later. This can contribute to warmer urban areas, although the exact effect depends on the material and its properties.

A is correct. Removing trees changes how much sunlight the surface reflects, how much water returns to the air through evapotranspiration, and how the land stores and releases heat. These changes affect several parts of the local heat budget.

A is correct. Convection involves the movement of air and the transfer of heat with that moving air. In the atmosphere, this transports heat vertically, for example as warmer air rises.

A is correct. The tropics receive more solar energy than they lose on average, while high latitudes lose more than they receive. Winds and ocean currents transport some heat from lower toward higher latitudes, helping reduce this imbalance.

The correct answer is A. The tropics receive more solar energy than the polar regions, creating a heat surplus near the equator and a deficit near the poles. Atmospheric and oceanic circulation help redistribute this energy around Earth.

The correct answer is A. When water is available at a moist surface, energy can be used to evaporate it, transferring energy as latent heat. This leaves less energy available to raise the surface temperature than would be available over a similarly heated dry surface.

The correct answer is A. Albedo affects how much incoming solar radiation a surface reflects, but temperature also depends on factors such as moisture, heat capacity, atmospheric conditions, and the movement of energy. Therefore, albedo alone cannot determine a region’s temperature.

The correct answer is A. Conduction transfers heat through direct contact. At Earth’s surface, the ground can conduct heat to the thin layer of air touching it, making this a direct example of conduction in surface heat exchange.

The correct answer is B. In the standard 100-unit heat-budget model, the 35 units are the portion of incoming solar energy returned to space by reflection from clouds and Earth's surface and by atmospheric scattering. This is reflected solar energy, not heat emitted by the surface.

The correct answer is C. With other factors unchanged, less reflection by clouds means less incoming solar energy is sent back to space. More energy is therefore available to be absorbed by the Earth system, so net solar absorption increases.

The correct answer is B. Greenhouse gases such as water vapour and carbon dioxide absorb strongly in parts of the longwave spectrum emitted by Earth, while much incoming solar energy is at wavelengths that pass through the atmosphere more readily. The atmosphere is not perfectly transparent or uniformly absorbing at every wavelength.

The correct answer is A. The surface's absorbed energy is divided among several energy transfers: evaporation uses energy as latent heat, sensible heat is transferred to the air, and the surface emits longwave radiation. Only the remaining portion directly changes the surface's stored heat and temperature.

The correct answer is B. Positive net radiation means there is a net energy gain, but that energy does not have to raise the surface temperature immediately. Some can supply latent heat for evaporation or be transferred to the air or nearby areas.

The correct answer is B. Lower albedo means less incoming solar energy is reflected and more is absorbed. Lower evaporation also reduces the energy used as latent heat, leaving more energy available to warm the surface. Other local conditions can affect the final temperature.