Could someone describe the difference between gravity waves and
gravitational waves. I recently saw a picture and caption from a magazine
on a bulletien board that said gravity waves were responsible for the
formation of noctilucent clouds (clouds with ripples). The caption also
differentiated between gravity waves and gravitational waves. I thought I
had a vague idea about one of these concepts but now think I have been to
one too many rock concerts. Thanks in advance for any help.