Answer to Question 1
ANSWER: Volcanic eruptions rich in sulfur can produce red sunsets. Such red sunsets are actually produced by a highly reflective cloud of sulfuric acid droplets, formed from sulfur dioxide gas injected into the stratosphere during powerful eruptions. Two examples are the Mexican volcano El Chichn in 1982 and the Philippine volcano Mt. Pinatubo in 1991. These fine particles, moved by the winds aloft, circled the globe, producing beautiful sunrises and sunsets for months and even years after the eruptions. These same volcanic particles in the stratosphere can turn the sky red after sunset, as some of the red light from the setting Sun bounces off the bottom of the particles back to Earths surface. Generally, these volcanic red sunsets occur about an hour after the actual sunset (see Fig. 20.12).
Answer to Question 2
ANSWER: Haze can scatter light from the rising or setting Sun in a way that produces bright light beams, or crepuscular rays, radiating across the sky. When the bright light beams appear to converge toward the part of the horizon opposite from the Sun, the beams of light are called anticrepuscular rays.
On the slopes of Chimborazo, a 6,310 m high volcanic peak in the Andes Mountains of Ecuador, Alexand
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Under ideal conditions, a single cell of the bacterium E. coli would divide every 20 minutes to ...
For the circuit in Figure 1, assume ideal diodes. The peak inverse voltage is approximately