Ship-wave-shape wave clouds induced by Juan Fernandez
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Ship-wave-shape wave clouds induced by Juan Fernandez Islands, off Chile

May 11, 2011
A combination of cloud, wind and tall islands created a striking pattern over the South Pacific Ocean off the coast of Chile on April 29, 2011. The Moderate Resolution Imaging Spectroradiometer (MODIS) flying aboard the Aqua satellite captured this true-color image of two ship-wave-shape clouds induced by Juan Fernandez Islands on that same day.

The cloud pattern is given its name because the ripples in the clouds are reminiscent of the V-shape wakes left behind boats traveling in water. In this case, however, the air is moving around high mountain peaks that are stationary, and the patterns are caused as the air is swept over and around the mountains, causing a ship-wave like pattern on the lee side. The disturbed air rises and falls causing peaks and troughs. Rising air cools, and because the air is moist, clouds form on the peaks. As the air falls, it warms and the clouds dissipate. The formation and dissipation of clouds creates the striking cloudy-and-clear pattern.

The Juan Fernandez Islands are volcanic in origin, rising from lava flows from the Juan Fernandez hotspot a million years ago or more. The islands of Robinson Crusoe and Alejandro Selkirk have very tall peaks (3,005 feet and 4,360 feet, respectively) that are high enough to disrupt clouds, creating several interesting patterns that can be seen from space. In this image, the island of Alejandro Selkirk is on the left and Robinson Crusoe is on the right.

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