Earth Science Gallery
2002 EARTH SCIENCE VIDEOTAPES
Tape Title
Record ID
Date Produced
TRT:
Synopsis
URBAN HEAT ISLANDS INCREASE FAINFALL AROUND CITIES
G02-048 6/18/02 00:07:05 NASA researchers have for the first time used a rainfall-measuring satellite to confirm that "urban heat-islands" create more summer rain over and downwind of major cities, including Atlanta, Dallas, San Antonio, and Nashville. Scientists found that urban areas with high concentrations of buildings, roads and other artificial surfaces retain heat and lead to warmer surrounding temperatures, and create urban heat-islands. This increased heat may promote rising air and alter the weather around cities. A recent United Nations study estimates that 80% of the world's population will live in cities by 2025, so a better understanding of the impact of urban land use change on Earth's water cycle system is vital. The study appears in the July 2002 issue of the Journal of Applied Meteorology.
TAPE CONTENTS:
ITEM (1): Urban Rainfall Shadows - Using the world's first space-based rain radar, scientists found that mean monthly rainfall rates within 35 miles downwind of cities were, on average about 28% greater than the upwind region (regions shown in blue). In some cities, the downwind area exhibited increases as high as 51%. The images depict the urban rain effect east of the I-35 corridor in Texas (first image) and near the Atlanta/Birmingham region (second image).
Credit: NASA
ITEM (2): Animation of Urban Rainfall Effect - Cities tend to be one to 10 degrees Fahrenheit warmer than surrounding suburbs and rural areas and the added heat can destabilize and change the way air circulates around cities. Mostly during the warmer months, the added heat creates wind circulations and rising air that can produce clouds or enhance existing ones. Under the right conditions, these clouds can evolve into rain-producers or storms. It is suspected that converging air due to city surfaces of varying heights, like buildings, also promotes rising air needed to produce clouds and rainfall.
Credit: NASA
ITEM (3): Urban Heat Islands - Using a specially outfitted Lear Jet, NASA researchers collected thermal data about the Atlanta metro area. As shown here, that aircraft data is lined up with a larger image, taken from the orbiting Landsat 5 satellite. The image starts in "natural" color and immediately transitions to a daytime temperature reading, with white and red indicating highest temperatures, respectively, and blues indicating cooler temperatures. Notice how the buildings themselves help keep small areas cool, casting shadows across the pavement and walls of surrounding structures. As the city rotates, the data fades to a nighttime reading. Using the same color scale, you can see how much heat remains locked in the developed areas of the city, a phenomena which becomes instantly apparent as the picture zooms out again to show the long stripe of data draped across the terrain. These data were collected May 11 and 12, 1997. While daytime air temperatures on that date were only about 80 degrees, surface temperatures reached as much as 118 (F); nighttime air temperatures hovered between 50 and 55, but due to the heat sink, surface temperatures hung on as high as 75 degrees. (G00-015)
Credit: NASA
ITEM (4): Urban Heat Island - Cloud Formation - Atlanta's strong urban growth is being studied for a variety of reasons. One of the most dramatic areas of study concerns the way intense development may be affecting the region's climate. In the following animation, we see the outlines of Atlanta and Hartsfield Airport; the tiny dot in the lower left corner of Atlanta is the downtown skyline. As observed by one of the Geostationary Operational Environmental Satellite (GOES), clouds begin forming over the city and pick up strength and size as they develop, moving east. Research suggests that as the city holds onto heat at night, it creates a low pressure system, with hot air rising and cooler surrounding air rushing in to replace it. That cooler air condenses and forms thunderclouds. But now there's evidence suggesting the phenomenon may be more intense over heavily urbanized areas than in naturally occurring places. In the animation, red indicates the heaviest concentration of precipitation with thick, high clouds; green are less intense storm areas, and the thick white areas are dense surrounding clouds. Although most people probably don't realize it, GOES data is part of millions of people's everyday lives. GOES is actually a constellation of weather satellites used for many of the forecasts we see on television. In the context of this research, GOES data is being used to understand a complex weather system, rather than directly forecast coming storms. (G00-015)
Credits: NASA
ITEM (5): Urban Growth Fuels Heat Islands - In the past 17 years, urban growth in Atlanta has spread and blossomed, but not without dramatic changes to the surrounding area. Large patches of crop land have given way to commercial and residential developments, and industrialization along some of the main roadways have dramatically altered the face of Georgia's largest city. In this visualization, red and orange points indicate areas of highest urban growth. Researchers assembled data from Landsat satellites in the early 70's to the late 90's and created plots of growth over time, providing valuable context for more detailed studies of air quality, climate changes, and urban planning. This series of images, green and light blue spaces yield to ever spreading red and orange points. (G00-015)
Credits: NASA
ITEM (6): Animation of TRMM Satellite - The researchers took advantage of the world's first space-based rain radar aboard NASA's Tropical Rainfall Measuring Mission (TRMM) satellite to conduct the study. Earlier research has used ground-based instruments, including rain gauge networks, ground-based radar, or model simulations, to show that urban heat islands can impact local rainfall around cities like St. Louis, Chicago, Mexico City, and Atlanta. Although useful, many of these studies were limited to specific cities that had access to relevant data from special observation networks or computer model simulations. But satellites broaden the scope of such research by monitoring changes in rainfall patterns over urban areas on global scales over long periods of time. (G97-038)
Credits: NASA
[Urban Heat Island Movie]
NOTE: The material advertised on this page is a "Video File" and is strictly recommended for the media and production companies. This is NOT a finished production but does contain some narration.
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Earth Science Gallery
2002 EARTH SCIENCE VIDEOTAPES |
||||
|---|---|---|---|---|
Tape Title | Record ID | Date Produced | TRT: | Synopsis |
| URBAN HEAT ISLANDS INCREASE FAINFALL AROUND CITIES | G02-048 | 6/18/02 | 00:07:05 | NASA researchers have for the first time used a rainfall-measuring satellite to confirm that "urban heat-islands" create more summer rain over and downwind of major cities, including Atlanta, Dallas, San Antonio, and Nashville. Scientists found that urban areas with high concentrations of buildings, roads and other artificial surfaces retain heat and lead to warmer surrounding temperatures, and create urban heat-islands. This increased heat may promote rising air and alter the weather around cities. A recent United Nations study estimates that 80% of the world's population will live in cities by 2025, so a better understanding of the impact of urban land use change on Earth's water cycle system is vital. The study appears in the July 2002 issue of the Journal of Applied Meteorology. |
TAPE CONTENTS: |
||||
| ITEM (1): Urban Rainfall Shadows - Using the world's first space-based rain radar, scientists found that mean monthly rainfall rates within 35 miles downwind of cities were, on average about 28% greater than the upwind region (regions shown in blue). In some cities, the downwind area exhibited increases as high as 51%. The images depict the urban rain effect east of the I-35 corridor in Texas (first image) and near the Atlanta/Birmingham region (second image). Credit: NASA | ||||
| ITEM (2): Animation of Urban Rainfall Effect - Cities tend to be one to 10 degrees Fahrenheit warmer than surrounding suburbs and rural areas and the added heat can destabilize and change the way air circulates around cities. Mostly during the warmer months, the added heat creates wind circulations and rising air that can produce clouds or enhance existing ones. Under the right conditions, these clouds can evolve into rain-producers or storms. It is suspected that converging air due to city surfaces of varying heights, like buildings, also promotes rising air needed to produce clouds and rainfall. Credit: NASA | ||||
| ITEM (3): Urban Heat Islands - Using a specially outfitted Lear Jet, NASA researchers collected thermal data about the Atlanta metro area. As shown here, that aircraft data is lined up with a larger image, taken from the orbiting Landsat 5 satellite. The image starts in "natural" color and immediately transitions to a daytime temperature reading, with white and red indicating highest temperatures, respectively, and blues indicating cooler temperatures. Notice how the buildings themselves help keep small areas cool, casting shadows across the pavement and walls of surrounding structures. As the city rotates, the data fades to a nighttime reading. Using the same color scale, you can see how much heat remains locked in the developed areas of the city, a phenomena which becomes instantly apparent as the picture zooms out again to show the long stripe of data draped across the terrain. These data were collected May 11 and 12, 1997. While daytime air temperatures on that date were only about 80 degrees, surface temperatures reached as much as 118 (F); nighttime air temperatures hovered between 50 and 55, but due to the heat sink, surface temperatures hung on as high as 75 degrees. (G00-015) Credit: NASA | ||||
| ITEM (4): Urban Heat Island - Cloud Formation - Atlanta's strong urban growth is being studied for a variety of reasons. One of the most dramatic areas of study concerns the way intense development may be affecting the region's climate. In the following animation, we see the outlines of Atlanta and Hartsfield Airport; the tiny dot in the lower left corner of Atlanta is the downtown skyline. As observed by one of the Geostationary Operational Environmental Satellite (GOES), clouds begin forming over the city and pick up strength and size as they develop, moving east. Research suggests that as the city holds onto heat at night, it creates a low pressure system, with hot air rising and cooler surrounding air rushing in to replace it. That cooler air condenses and forms thunderclouds. But now there's evidence suggesting the phenomenon may be more intense over heavily urbanized areas than in naturally occurring places. In the animation, red indicates the heaviest concentration of precipitation with thick, high clouds; green are less intense storm areas, and the thick white areas are dense surrounding clouds. Although most people probably don't realize it, GOES data is part of millions of people's everyday lives. GOES is actually a constellation of weather satellites used for many of the forecasts we see on television. In the context of this research, GOES data is being used to understand a complex weather system, rather than directly forecast coming storms. (G00-015) Credits: NASA | ||||
| ITEM (5): Urban Growth Fuels Heat Islands - In the past 17 years, urban growth in Atlanta has spread and blossomed, but not without dramatic changes to the surrounding area. Large patches of crop land have given way to commercial and residential developments, and industrialization along some of the main roadways have dramatically altered the face of Georgia's largest city. In this visualization, red and orange points indicate areas of highest urban growth. Researchers assembled data from Landsat satellites in the early 70's to the late 90's and created plots of growth over time, providing valuable context for more detailed studies of air quality, climate changes, and urban planning. This series of images, green and light blue spaces yield to ever spreading red and orange points. (G00-015) Credits: NASA | ||||
| ITEM (6): Animation of TRMM Satellite - The researchers took advantage of the world's first space-based rain radar aboard NASA's Tropical Rainfall Measuring Mission (TRMM) satellite to conduct the study. Earlier research has used ground-based instruments, including rain gauge networks, ground-based radar, or model simulations, to show that urban heat islands can impact local rainfall around cities like St. Louis, Chicago, Mexico City, and Atlanta. Although useful, many of these studies were limited to specific cities that had access to relevant data from special observation networks or computer model simulations. But satellites broaden the scope of such research by monitoring changes in rainfall patterns over urban areas on global scales over long periods of time. (G97-038) Credits: NASA | ||||
[Urban Heat Island Movie]
NOTE: The material advertised on this page is a "Video File" and is strictly recommended for the media and production companies. This is NOT a finished production but does contain some narration.
[HOME] [Return to the Earth Science Catalog] [How to order videotapes]