The belt of low pressure and calm air lying along the equator is known as the
- A.Horse latitudes
- B.Doldrums
- C.Roaring forties
- D.Polar high
Correct answer
Explanation
The correct answer is B, the doldrums. Strong heating at the equator makes the air expand and rise, so surface pressure is low and horizontal winds are weak; sailing ships were often becalmed there. The rising air cools, condenses and gives the heavy convectional rainfall of the equatorial belt, and the zone where the trade winds of the two hemispheres meet here is the inter-tropical convergence zone.
Option A, the horse latitudes, is also a belt of calms but it lies near thirty degrees in the sub-tropical high pressure belt, where air sinks and the weather is dry. Option C, the roaring forties, names the strong westerlies of the southern ocean, the opposite of calm. Option D, the polar high, is the belt of cold heavy air over the poles from which the polar easterlies blow out.
Read the full article: Atmosphere and Winds: Layers, Pressure Belts and Jet Streams
Practice Questions
View allThe ozone layer, which absorbs ultraviolet radiation, lies in which layer of the atmosphere?
- A.Troposphere
- B.Stratosphere
- C.Mesosphere
- D.Thermosphere
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Ozone is concentrated in the lower and middle stratosphere, and because it absorbs ultraviolet radiation the temperature of this layer rises with height instead of falling.
Read the full explanation →The normal lapse rate of temperature in the troposphere is about
- A.6.5 degrees Celsius per kilometre
- B.1 degree Celsius per kilometre
- C.10 degrees Celsius per kilometre
- D.0.65 degrees Celsius per kilometre
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This is the average rate at which air temperature falls as one rises through the troposphere, and it explains why hill stations are cooler than the plains and why high peaks carry snow even in the tropics.
Read the full explanation →Meteors entering the earth's atmosphere burn up mainly in which layer?
- A.Stratosphere
- B.Mesosphere
- C.Thermosphere
- D.Exosphere
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Although the air there is thin, it is dense enough to heat a body moving at cosmic speed by friction, so most meteors glow and are destroyed in this layer and are seen from the ground as shooting stars.
Read the full explanation →Which gas forms the largest share of dry air by volume?
- A.Oxygen
- B.Nitrogen
- C.Argon
- D.Carbon dioxide
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It is comparatively inert, so it dilutes oxygen and slows combustion, and it enters living things mainly through the nitrogen cycle in which bacteria fix it in a usable form.
Read the full explanation →The warm and dry local wind known as the snow eater blows over which region?
- A.The eastern slopes of the Rockies in North America
- B.The northern slopes of the Alps in Europe
- C.The eastern slopes of the Andes in Argentina
- D.The northern edge of the Sahara
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The wind is the Chinook. It descends the leeward slope, is compressed and warmed as it sinks, and can raise the temperature sharply in a few hours; it melts or evaporates the snow cover, which is why herders call it the snow eater and why it is valued for exposing…
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