Question

near sunrise or sunset, the rays coming directly from the sun strike the atmosphere at a low angle. when the sun is 4° above the horizon: a. sunlight must pass through an atmosphere more than 12 times thicker than when the sun is directly overhead. b. most of the long wavelength radiation have been scattered away by the air molecules. c. rainbows are likely to occur. d. most of the short wavelength radiation have been scattered away by the cloud droplets.

Explanation:

When the sun is near the horizon (4° above in this case), sunlight has to travel through a much longer path in the atmosphere compared to when it is directly overhead. This longer - path causes more scattering of shorter - wavelength radiation (like blue and violet) by air molecules. Shorter - wavelength radiation is scattered more due to Rayleigh scattering. Cloud droplets are not the main scatterers for this phenomenon near sunrise/sunset. Rainbows occur under specific conditions of sunlight and raindrops and are not directly related to the sun's position near the horizon in this context. Long - wavelength radiation is scattered less.

Answer:

A. sunlight must pass through an atmosphere more than 12 times thicker than when the sun is directly overhead.