How does cloud cover factor into race strategy?

Richard Buck, managing director of the Monster Energy NASCAR Cup Series, and The Weather Channel's Kait Parker break down how and why cloud coverage affects racing. MORE: How does temperature affect a race? | Why does cloud coverage matter? "When you're dealing with hundreds of thousands of seconds separating a few positions every little bit counts," Buck explained. " ... You'll hear the crew chief and spotters and drivers sit on the end of pit road during the qualifying session to catch a glimpse of the cloud coverage to put down their best lap." Clouds can change the temperature by nearly 20 degrees, and according to Parker, a car will perform much better with under cloudy conditions rather than direct sunlight.