Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Saharan Dust Affects Thunderstorm Behavior in Florida

12.01.2005


Saharan Dust Blowing off Northwest Africa: This is an image of dust storms taken by NASA’s SeaWiFS satellite, taken on Feb. 28, 2000. Click on image to enlarge. Credit: NASA


A Microscopic Look at Dust: This particle of dust was magnified 12,000 times. Click on image to enlarge. Credit: USGS


People that live in Florida would expect the sands from the state beaches to blow into the air, and usually don’t think of the sands and dust from the Saharan Desert twirling around them. However, winds do carry the desert dust across the Atlantic Ocean, and scientists have been studying what they do to Florida Thunderstorms.

Scientists have discovered that these tiny particles of dust from the Saharan desert can affect thunderstorms in Florida in various ways. Dust affects the size of a thunderstorm’s "anvil" or top, the strength and number of warm updrafts (rising air), and the amount of rain that builds up and falls from the "heat generated" or convective thunderstorms.

Findings on the "Impact of Saharan Dust on Florida Storm Characteristics" were presented at the 2005 annual meeting of the American Meteorological Society on Jan. 11 at the San Diego Convention Center in San Diego, Calif. Susan C. van den Heever, Gustavo G. Carrio, William R. Cotton, Paul. J. DeMott and Anthony J. Prenni, all of Colorado State University, Fort Collins, Colo. co-authored a study which will appear in a forthcoming issue of the Journal of Atmospheric Sciences.



Working with her colleagues, van den Heever found that when Saharan dust is in the air, the thunderstorm anvils created by Florida’s convective thunderstorms tend to be a little smaller in area, but they tend to be better organized and thicker. This affects the amount of incoming sunlight and warmth reaching the ground, which can have effects on long-term climate. Over time, more sunlight would warm temperatures, less sunlight would cool temperatures.

The researchers also noticed that the updrafts of warm moist air, which build into thunderstorms, were stronger, and that there were more of these updrafts produced in the presence of the dust. These updrafts also carry tiny particles of pollution called aerosols up into all levels of the building thunderclouds.

Florida residents not only see more updrafts developing during dust events, but the dust affects the amount of rainfall that reaches the ground. Dust is an aerosol, and aerosols or little particles serve as the center or nuclei (called a cloud condensation nuclei) for cloud droplets to form around. These cloud droplets then combine to form raindrops which fall to the ground. As such, aerosols affect the production of rainfall.

There are three types of nuclei that Saharan dust can be. They can act as the center or nuclei for water vapor as a CCN, GCCN (Giant Cloud Condensation Nuclei) and IN (Ice Nuclei), where ice forms around a dust particle center. Van den Heever used a computer model to see how the atmosphere and clouds react with Saharan dust and without the desert dust. She then compared the results and found something unusual. The dust increased the number of centers or nuclei for raindrops and decreased the amount of rainfall at the Earth’s surface.

Nuclei or centers for droplets in a cloud compete for a limited amount of water vapor and liquid water to form raindrops. When there are many particles that act as a center for water vapor, there is less water for each center, resulting in smaller cloud droplets. As such, it is less likely that raindrops will form when droplets combine.
the stratosphere. Click on image to enlarge. Credit: NASA

The scientists also found that greater concentrations of Giant CCN (GCCN) as well as ice nuclei initially resulted in more rainfall reaching the surface. However, as the storms continued to develop, the two types of nuclei were removed from the storms by the precipitation and these nuclei then had less of an effect on the amount of rain reaching the surface. The scientists concluded that the overall effect of the Saharan dust on the surface rainfall was to reduce it.

The scientists used data from NASA’s CRYSTAL-FACE (Cirrus Regional Study of Tropical Anvils and Cirrus Layers – Florida Area Cirrus Experiment) field campaign to examine the affects of increased numbers of nuclei from the dust and pollutants. The purpose of the CRYSTAL-FACE mission was to study cirrus clouds to improve forecasts of future climate change.

The scientists concluded that Saharan dust can have a major impact on the amount of rainfall produced by thunderstorms in Florida. Also, because dust affects the size and thickness of thunderstorm anvils, the changes affect the amount of sunlight reaching Earth and being reflected by the clouds, which have implications for a changing climate. Finally, this research can also help answer questions about how tiny particles called aerosols and other pollutants move around the world in the upper atmosphere.

Rob Gutro | EurekAlert!
Further information:
http://www.nasa.gov/vision/earth/lookingatearth/florida_dust.html
http://www.gsfc.nasa.gov

More articles from Earth Sciences:

nachricht Northern oceans pumped CO2 into the atmosphere
27.03.2017 | CAGE - Center for Arctic Gas Hydrate, Climate and Environment

nachricht Weather extremes: Humans likely influence giant airstreams
27.03.2017 | Potsdam-Institut für Klimafolgenforschung

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Northern oceans pumped CO2 into the atmosphere

27.03.2017 | Earth Sciences

Fingerprint' technique spots frog populations at risk from pollution

27.03.2017 | Life Sciences

Big data approach to predict protein structure

27.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>