Skip all navigation and jump to content Jump to site navigation
NASA Logo - Goddard Space Flight Center

+ NASA Homepage

    
Goddard Space Flight Center
About MODIS News Data Tools /images2 Science Team Science Team Science Team

   + Home
ABOUT MODIS
 

October 20, 2014

October 19, 2014

October 18, 2014

October 17, 2014

October 16, 2014

October 15, 2014

October 14, 2014

 

 

April 30, 2014 - Tracks from Zavodovski and Mount Michael volcanoes, South Sandwich Islands (false color)
Tracks from Zavodovski and Mount Michael volcanoes, South Sandwich Islands (false color) Image used for Spacing Purposes
Satellite: Aqua
Date Acquired: 4/19/2014
Resolutions: 1km (241.9 KB)
500m (929.4 KB)
250m (2.2 MB)
Bands Used: 7,2,1
Credit: Jeff Schmaltz
MODIS Land Rapid Response Team,
NASA GSFC

The South Sandwich Islands, in the far southern Atlantic Ocean, are often shrouded with thick cloud, making it difficult to view the region from space. Sometimes, however, the use of false-color imagery can be used to reveal events that would otherwise be obscured under cloud cover.

The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite flew over the South Sandwich Islands on April 19, 2014 and acquired this false-color image of the cloudy scene.

This false-color image uses a combination of non-visible (middle infrared and infrared) and visible (red) light captured in bands 7, 2, and 1, respectively, to distinguish clouds from snow and ice. Here the ice-covered islands appear bright turquoise, the clouds light turquoise and the water in the ocean appears deep black. Because the volcanic plume is a moist mixture of gas and ash, it reflects all three forms of light relatively well, so it appears nearly white.

In the north of this image, a thin plume of white rises from the volcano on Zavodovski island, the northernmost of the South Sandwich Islands and streams to the northeast. Further south, a wider white plume can be seen blowing across the Atlantic Ocean. This plume rises from the Mount Michael volcano, which is a young and frequently active stratovolcano located on Saunders Island, near the center of the South Sandwich Island chain.

The white plume from Mount Michael forms a chain of swirling eddies as it blows to the northeast. To the south, similar eddies can be seen behind three other islands. These are known as Von Kármán vortices. These vortices can form nearly anywhere that fluid flow is disturbed by an object. Because the atmosphere behaves like a fluid, when streaming air hits a blunt object, such as a mountain peak, the wind is forced around the object. The disturbance in the flow of the wind propagates downstream in a double row of vortices that alternate their direction of rotation, much like the eddies seen behind a pier in a river as water rushes past.

FirstGov logo Privacy Policy and Important Notices NASA logo

Curator: Brandon Maccherone
NASA Official: Shannell Frazier

NASA Home Page Goddard Space Flight Center Home Page