Which method uses a mirror divided into squares to estimate cloud cover?

• A. Daylight Hours
• B. Sunshine Hours
• C. Cloud Cover
• D. Dew Point

Answer: (C)

Estimating cloud cover is about judging how much of the sky is obscured by clouds, and using a mirror divided into squares gives you a fixed grid to make that judgment consistent. By looking at the sky through the grid, you can count how many squares are cloudy versus clear and convert that into a fraction or oktas (the eight-part scale) to express the amount of cloud. This grid method reduces personal guesswork and makes observations repeatable in fieldwork. The other options measure different things—how long daylight lasts, how much sunshine occurs, or the air’s moisture (dew point)—so they aren’t about estimating cloud cover.