This unusual image shows a part of the Pacific Ocean northwest of Australia and exemplifies the interaction between the atmosphere and the quiet sea of the Indian Ocean. Atmospheric gravitational waves develop from the rise and fall of air in vertical undulations. If air masses sink during the undulations, they roughen the surface of the water. In the satellite image, this section of the water surface is darker than the smooth surface between the wave troughs. As can be seen in the upper part of the picture, clouds develop above the wave crests quite often. Picture taken on October 27, 2010Sensor: Terra MODIS