New Orleans, Louisiana

This image of the area surrounding the city of New Orleans, 
Louisiana, in the southeastern United States demonstrates the 
ability of multi-frequency imaging radar to distinguish 
different types of land cover.  

The dark area in the center 
is Lake Pontchartrain. The thin line running across the lake 
is a causeway connecting New Orleans to the city of 
Mandeville.  Lake Borgne is the dark area in the lower right 
of the image.  The Mississippi River appears as a dark, wavy 
line in the lower left.  

The area is located at 30.10  degrees north latitude 
and 89.1 degrees west longitude. The area shown is 
approximately 100 kilometers (60 miles) by 50 kilometers (30 
miles).The image was acquired by the Spaceborne 
Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) 
during orbit 39 of space shuttle Endeavour on October 2, 
1994.  SIR-C/X-SAR radars illuminate Earth with microwaves
allowing detailed observations at any time, regardless of weather
or sunlight conditions.  The colors in this image were obtained
using the following radar channels: red represents the L-band 
(horizontally transmitted and received); green represents the 
C-band (horizontally transmitted and received); blue 
represents the L-band (vertically transmitted and received). 

The green areas are primarily vegetation consisting of swamp 
land and swamp forest (bayou) growing on sandy soil, while 
the pink areas are associated with reflections from buildings 
in urban and suburban areas. 


Questions:

a) What do you think the white dots on the Mississippi River are?

b) Using the street map of New Orleans, locate the French Quarter
and the New Orleans Lakeshore Airport.  How do these places
appear on the image?

c) The ''urban island effect'' partially results from paving
widespread areas of soil and vegetation with cement and asphalt. 
During the day, urbanized areas tend to be hotter than the
surrounding countryside. This is also true for the entire summer
season.  

(i) Explain why such urbanized areas tend to be hotter, using New
Orleans as an example. Use terms like "specific heat capacity,"
"sensible heat," and "latent heat."  

(ii) How is urbanization in New Orleans similar to
desertification and/or deforestation?

(iii) Also, speculate as to why cities tend to get more frequent
and violent thunderstorms than rural areas.[Hint: think about
sensible heat and the movement of air masses and water vapor.]