2001 EARTH SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| ANOTHER ELEMENT TO CLIMATE CHANGE: HOW DUST INHIBITS RAINFALL | G01-038 | 05/11/01 | 00:09:58 | Climate change results from more than just the effects of greenhouse gases. According to recent findings, a newly discovered element in climate change is the effect of dust on rainfall. Windblown dust can choke rain clouds and inhibit rainfall. This reduction of precipitation in the clouds can cause drier soil, which in turn raises more dust, thus providing a possible feedback loop to further decrease rainfall and exacerbate drought conditions.
In addition to dust, it is known that both aerosols (particles) in smoke from biomass burning and urban pollution also inhibit rainfall production. Through their ability to suppress rainfall, each of these three elements could have a major effect on regional and global climate.
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TAPE CONTENTS: |
| ITEM (1): Dust Images From Around the World) - The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) on board the Orb View-2 Satellite, has captured images of dust storms around the globe. According to the recent studies, high dust frequency is not necessarily a result of the decreased rainfall, but rather its cause.
1) Texas, United States, January 3rd, 2000 (200 miles across)
2) Off the northwestern coast of the African Continent, February, 26th 2000- a dust storm the size of Spain
3) Mediterranean Sea
a)July 18th 2000 from north Africa towards Italy
b) April 18th 2001 northward from Egypt
All three continents bordering the Mediterranean Sea are subject to affects of dust storms.
4) Middle East, May 20th 1999
5) China, April 17, 2001 The image shows an almost continuous long sinuous band of dust and possibly pollution extending from the East Sea along the China coast, over northern Japan and extending up to Kamchatka.
Courtesy: NASA/ ORBIMAGE
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| ITEM (2): Three Contributing Factors for Rainfall Inhibition - Dust is only one of three types of aerosols which can inhibit rainfall. Previous studies have shown that aerosols from biomass burning (i.e. burning of plant material such as forests, grasslands, and agricultural waste ) and aerosols from man-made pollution also contribute to disturbing the rainfall process.
This animation highlights the power of these three factors vs. the normal conditions of the rainfall process. In this virtual world, a dust storm rises from arid conditions. Biomass burning sends smoke and an industrial complex adds pollutants into clouds and the atmosphere, thus preventing any rainfall.
The cloud on the left shows rainfall production in normal conditions.
Courtesy: NASA
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| ITEM (3): Methodology of Rainfall Production - Normal rainfall droplet creation involves water vapor condensing on particles in clouds. The droplets eventually coalesce together to form drops large enough to fall to Earth. However, as more and more dust particles (aerosols) enter a rain cloud, the same amount of water becomes spread out. These smaller water droplets scatter and are prevented from coalescing and growing large enough for a raindrop. Thus, the cloud yields less rainfall over the course of its lifetime.
This animation compares a normal rain producing cloud, (left) with the lack of rain produced from a cloud full of aerosols from biomass burning (right.) Courtesy: NASA
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| ITEM (4): Global Precipitation Maps - This visualization highlights the global rainfall averages for a two and a half year period (from January 1998 to October 2000) on the swath of territory covered by the Tropical Rainfall Measuring Mission (TRMM) satellite. Courtesy: NASA/NASDA
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| ITEM (5): B-Roll of Aerosol Producing Conditions - Images of drought conditions and production of aerosols i.e. biomass burning and industrial pollution sources. Courtesy: NASA
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| ITEM (6): TRMM Satellite - The Tropical Rainfall Measuring Mission (TRMM) satellite, a joint US-Japanese mission, measures rainfall amounts over the tropic regions, as well as the corresponding energy released, energy which helps to fuel the atmospheric circulation that shapes both weather and climate around the globe. Courtesy: NASA
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| ITEM (7): SeaWiFS Instrument - The SeaWiFS Mission is a part of NASA's Earth Science Enterprise, which is designed to look at our planet from space to better understand it as a system in both behavior and evolution. Courtesy: NASA
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