Extreme Wind Damage: Wind damage may look like this. Although the shingles are still generally in place, these shingles have pulled away from the nails and only the adhesive is holding them in place. Usually this damage is not visible from the ground.

Subtle wind damage: The chalk mark underlines a crease in this shingle. Wind has caused this shingle to become unsealed, so it will flap in the wind causing the crease. Soon, normal weather will tear the tab completely off. Missing tabs are a sure sign of wind damage and are usually visible from the ground.

Hail damage:

Once the granules are gone, there is nothing left to protect the body of the shingle and it deteriorates rapidly.

Check out this subtle crack from a losend shingle, just above the chalk line. 
This leads to more damage over time if not addressed.

scroll down for detailed look at subtle wind damage

Have a flat roof?  click here

Common Roof Damage