#19: Humidity Often Rises as Temperature Falls
Cooler air can hold less water vapor than warmer air, so relative humidity commonly increases as the temperature drops during an eclipse. The amount of moisture present may have changed very little; the percentage rises because the air has cooled closer to its saturation point. Measurements from different eclipses have shown a range of responses, including delayed increases, brief oscillations, or changes too small to separate confidently from ordinary weather. Wind, soil moisture, cloud cover, vegetation, and the starting humidity all affect the result.
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