NASA Photo ID: STS055-151-120     File Name: 10073202.jpg

Film Type: 4x5 CN                 Date Taken: 05/06/93

Title: STS-55 Earth observation of the Timor Sea

Description:

STS-55 Earth observation taken from Columbia, Orbiter Vehicle (OV) 102,
shows  the Timor Sea along the south coast of Timor. The sunglint pattern
shows a  sharp boundary in sea surface temperature, with cooler water along
the coast  and warmer water offshore. The sunglint brightness reveals water
surface  roughness with bright indicating smooth water and dark
representing rough  water. Cooler water is smoother because it acts to
stabilize the atmospheric  boundary layer, while the warm water acts to
destabilize the atmosphere.   Another indication of water temperature is
the cloud pattern.  Advection  within the atmosphere as a result of warming
at the sea surface forms  low-level clouds with the small, popcorn-like
appearance seen in upper right  corner of the photograph.  The cool water,
on the other hand, is relatively  free of the popcorn-like clouds.  The
distribution of the clouds indicates  that the wind is blowing toward the
upper right corner of the photograph.   Also note the line of low-level
popcorn clouds situated along the boundary  between the two water masses
and over the cooler water.  According to NASA  scientists studying the
STS-55 photography, this indicates the likely  presence of a vortex within
the atmosphere, where the air over the warm water  is rising and the air
over the cooler water is sinking.  This particular  cloud pattern only
appears where the water mass boundary is nearly parallel  to the wind
direction.  It does not appear where the boundary shifts  orientation
(bottom of the photograph) and is nearly perpendicular to the  wind
direction.