Featured Research

from universities, journals, and other organizations

NASA Study Improves Ability To Predict Aerosols' Effect On Cloud Cover

Date:
August 19, 2008
Source:
NASA/Goddard Space Flight Center
Summary:
Using a novel theoretical approach, researchers from NASA and other institutions have identified the common thread that determines how aerosols from human activity, like the particles from burning of vegetation and forests, influence cloud cover and ultimately affect climate. The study improves researchers' ability to predict whether aerosols will increase or decrease cloud cover.

Small soot and sulfate aerosols are seen in these microscope slides. Trapped in the atmosphere, these tiny particles can have an important effect on climate.
Credit: Mihály Pósfai, Arizona State University

Using a novel theoretical approach, researchers from NASA and other institutions have identified the common thread that determines how aerosols from human activity, like the particles from burning of vegetation and forests, influence cloud cover and ultimately affect climate. The study improves researchers' ability to predict whether aerosols will increase or decrease cloud cover.

Related Articles


"We connected the dots to draw a critical conclusion, and found evidence over the Amazon that traces the direct path of the effect of human activity on climate change by way of human-caused aerosols," said study co-author Lorraine Remer, a physical scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "During the dry season in the Amazon, the only aerosols of any magnitude are from smoke emerging from human-initiated fires."

It is well documented from previous studies that aerosols play an essential role in how clouds develop. With this knowledge, a team comprised of Remer, Ilan Koren of the Weizmann Institute in Rehovot, Israel and J. Vanderlei Martins of the University of Maryland Baltimore County set out to explore one of the least understood but most significant aspects of climate change caused by human activity: the connection between a change in the amount of human-caused aerosols and change in the structure of clouds. Findings from their study will be published tomorrow in the journal Science.

"Scientists have observed instances where increases or decreases in the amount of these tiny particles have increased and decreased cloud cover in different places and times," said Remer. "We saw an example of this ourselves: increased aerosols over the Amazon produced less cloud cover. Over the Atlantic Ocean, however, increased aerosols actually produced more cloud cover. We wanted to know what the link was between these different outcomes from varying amounts and types of aerosols. This paper gives us a clear picture of what is occurring."

The team developed an analytical model, or line of thinking that combined knowledge of cloud development, satellite observations and mathematical calculations of aerosol concentration and cloud properties in an effort to explain how the two opposing effects of aerosols on clouds can influence cloud coverage and life cycle.

"This result helps us understand aerosols' effect on a cloud's mass and lifetime -- how long it will provide cloud cover, how deep the clouds will be, and when and where it will rain," said Remer. "This improved understanding leads to prediction and prediction can help us plan and perhaps prevent some of the potential consequences of putting aerosols from human activity into the atmosphere."

To test their model, Remer's team used aerosol and cloud observations from NASA's Terra satellite of the Amazon during the 2005 dry season The season offers stable weather conditions and an abundance of human-caused aerosols from fires, set to clear new land and burn through old pastures to prepare the land for the next crop season.

Aerosols are the tiny particles that make up smoke, dust, and ocean spray. Traveling on wind currents, aerosols move from their source and into the atmosphere, where they become individually encased by water and turn into the droplets that combine to create clouds.

Cloud microphysics makes clear that the larger the number of aerosol particles suspended in air the less water in the atmosphere is available for condensation on each individual particle. Under these conditions, a cloud will have a much larger number of small droplets. The smaller the droplets, the longer it will take for a cloud to rain. Aerosol-rich clouds like this spread out by winds, produce less rainfall, and last longer, creating more cloud cover.

However, aerosols also influence clouds through their ability to absorb heat from the sun. The trapped heat causes the atmospheric layer to warm up, and changes the environment in which the cloud develops. The overall result is to make the environment less hospitable for cloud growth. Even the smallest resulting changes in cloud cover can significantly warm or cool the atmosphere and change when and where fresh water will be available in the region.

"As we'd expected in applying our model, increased smoke from the fires created clouds rife with a more pronounced radiative effect -- rich with human-caused aerosols that absorbed sunlight, warmed the local atmosphere, and blocked evaporation. This led to reduced cloud cover over the Amazon," said co-author Martins. "And it's encouraging to know the science behind our model should stand no matter the region."


Story Source:

The above story is based on materials provided by NASA/Goddard Space Flight Center. Note: Materials may be edited for content and length.


Cite This Page:

NASA/Goddard Space Flight Center. "NASA Study Improves Ability To Predict Aerosols' Effect On Cloud Cover." ScienceDaily. ScienceDaily, 19 August 2008. <www.sciencedaily.com/releases/2008/08/080814163554.htm>.
NASA/Goddard Space Flight Center. (2008, August 19). NASA Study Improves Ability To Predict Aerosols' Effect On Cloud Cover. ScienceDaily. Retrieved December 18, 2014 from www.sciencedaily.com/releases/2008/08/080814163554.htm
NASA/Goddard Space Flight Center. "NASA Study Improves Ability To Predict Aerosols' Effect On Cloud Cover." ScienceDaily. www.sciencedaily.com/releases/2008/08/080814163554.htm (accessed December 18, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Thursday, December 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) — The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Arctic Warming Twice As Fast As Rest Of Planet

Arctic Warming Twice As Fast As Rest Of Planet

Newsy (Dec. 18, 2014) — The Arctic is warming twice as fast as the rest of the planet, thanks in part to something called feedback. Video provided by Newsy
Powered by NewsLook.com
Ivory Trade Boom Swamps Law Efforts

Ivory Trade Boom Swamps Law Efforts

Reuters - Business Video Online (Dec. 17, 2014) — Demand for ivory has claimed the lives of tens of thousands of African elephants and now a conservation report says the illegal trade is overwhelming efforts to enforce the law. Amy Pollock reports. Video provided by Reuters
Powered by NewsLook.com
Indictments in West Virginia Chemical Spill Case

Indictments in West Virginia Chemical Spill Case

AP (Dec. 17, 2014) — A grand jury indicted four former executives of Freedom Industries, the company at the center of the Jan. 9, 2014 chemical spill in Charleston, West Virginia. The spill contaminated the Elk River and the water supply of 300,000 people. (Dec. 17) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins