What causes a cloud to appear dark?
A cloud appears white because cloud droplets scatter all wavelengths of visible light in all directions. As a cloud grows larger and taller, more sunlight is reflected from it and less light can penetrate all the way through. Since little light reaches the underside of the cloud, little light is scattered, and the cloud base appears dark. At the same time, if droplets near the cloud base grow larger, they become less effective scatterers and better absorbers. As a result, the meager amount of visible light that does reach this part of the cloud is absorbed rather than scattered, which makes the cloud appear even darker.
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Which of the following climate types is the most abundant on Earth?
A. dry climate B. moist continental climate C. moist subtropical mid-latitude climate D. moist tropical climate
Which of the following components of the atmosphere are most helpful in the cleansing of the air?
A) Hydroxyl radicals B) Ozone C) Radon D) Sulfur dioxide
Where do most shield volcanoes form—on the ocean floor or on the continents?
What will be an ideal response?
When an eruption cloud spills downslope from the crater rim, it forms a(n) _______________ flow
Fill in the blank with correct word.