Dear Tom,
Wind blowing over a lake’s surface creates the waves we see coming toward the shore. Shouldn’t waves radiate out in all directions and should we not observe waves going away from the shore as well?
Richard Shure, Evanston

Dear Richard,
Wind blowing over water creates waves, but those waves are always generated with movement in the same direction as the wind. Once a wave is created (moving in a single direction), other factors can influence its further motion. Factors include the reflection of waves off opposing shorelines, depth of water (shallower water will cause waves to turn toward the shore), and the shape of the shoreline. When winds blow offshore, primary wave motion will be offshore as well, but interference from reflected waves and shallow depth as you approach the shoreline often results in smaller wavelets moving onto windward beaches.