2. Cloud Cover

How do meteorologists measure cloud coverage?

Meteorologists measure cloud coverage in OKTAS (eighths). 
0 oktas means the sky is clear, 8 oktas means the sky is covered with clouds, and 4 oktas means half of the sky is cloudy. 

Example 1

Example 2

Example 3

Example 4

Example 5

Why is it important to measure cloud coverage?