Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.
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Question: Question: Smog is a visible form of what? Answer: air pollution

Answer: Smog clouds the city of Los Angeles, California. Visible air pollution in the form of smog is a sign that the air is unhealthy.

Question: Question: How do we describe chemical reactions? Answer: chemical equations

Answer: Chemical reactions are described using chemical equations.

Question: Question: What is the minimum number of times a partial lunar eclipse will occur each year? Answer: two

Answer:
Partial lunar eclipses occur at least twice a year, but total lunar eclipses are less common. The Moon glows with a dull red coloring during a total lunar eclipse ( Figure below ).