Google Earth, as well as being a fantastic tool for crimestopping, also can be used to beautifully illustrate the wave phenomenon known as diffraction–the tendency for wavefronts to spread out when they pass through narrow gaps.
Waves spread like this because every point on the wavefront can be considered a source of secondary, circular wavelets. When a wavefront is unimpeded, this continuous line of secondary wavelets interferes in such a way that the wave shape is preserved. When a wavefront reaches a gap, however, only the secondary wavelets that come from the gap contribute to the new wavefront, thus producing the hemispherical form.
Fabrizio Logiurato, a physics post-doc based at Trento University in Italy documents many more examples with some challenging equations in his recent paper.
Can you find any examples of diffraction using Google Earth?
Image Credit: Google Earth via Fabrizio Logiurato.