When asphalt shingles begin to age the tar strip on the underside of the shingles that seals to the one underneath it can dry up and become unsealed. Then when a wind storm hits they can then be ripped off as shown in the picture on the left. Sometimes this occurs with relatively new shingles because the manufacturer produced a batch of shingles with too thin a tar strip. Some brands provide better adhesion than others. Ask me for more details.