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