Wave Clouds over North of Iran, and off the Coasts of Mazandarān – April 13, 2011

Satellite: Terra / Date Acquired: 13/4/2011 / Resolutions: 1km / Bands Used: 1,4,3
Credit: Jeff Schmaltz MODIS Land Rapid Response Team, NASA GSFC

As the inset image shows, an intricate pattern of dust and clouds illustrate strong winds blowing over the Caspian Sea, and creating a formation known as wave clouds. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite captured this true-color image on April 13, 2011.

On that day, a thick layer of dust had also obscured the south-western parts of Iran, north-western tips of the Persian Gulf, the whole Kuwait, north-eastern parts of the peninsula, and some central and southern parts of Iraq. Some dust particles had reached by as far as the shores and some western parts of Turkmenistan where the pressure system over the Caspian region had pushed them off the coasts of Azerbaijan, Armenia, Georgia, and Turkey.

Along the northern shores of Iran, lines of clouds lie in parallel rows just over and also off the coasts of the Mazandarān province of the country. The clouds are forming at the crests of waves within the atmosphere.

As dry wind blows towards the southeast, it pushes into a wall of warmer, moist air that lies over the Mazandarān province. As these two air masses collide, the cool air pushes under the warmer layer, causing it to rise. As the warm air rises, it loses heat and cools, and falls again. These undulations cause a wave effect in the atmosphere.

At the top of the high-altitude waves, the colder air cannot hold as much moisture as warmer air, and the clouds form by condensation. Although this is a complex event, when seen from space, the result is a simple, but beautiful white patterns across the land as well as the sea.

Towards the southwest, the clouds have been squeezed together, barely beholding their parallel patterns. That has been resulted by the high wall of Alborz Mountains preventing the clouds to move further south into the central regions of Iran.

The clouds are forming at the peak of the atmospheric wave. Underneath these peaks, the land and the sea are undisturbed, because the peak of the wave is far above the ground and the water's surface.

The concept behind some parts of this post as well as the image has been derived from the NASA’s MODIS website. Image credits goes to Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC.