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

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>