Featured Research

from universities, journals, and other organizations

NASA Finds Polluted Clouds Hold Less Moisture And Cool Earth Less

Date:
January 6, 2005
Source:
NASA/Ames Research Center
Summary:
A NASA study found some clouds that form on tiny haze particles are not cooling the Earth as much as previously thought. These findings have implications for the ability to predict changes in climate.

An unusually high number of ship tracks are visible in the clouds off of the coasts of France and Spain in these Moderate Resolution Imaging Spectroradiometer (MODIS) images from the Aqua satellite and Terra satellites, captured within hours of each other on January 27, 2003.
Credit: Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC

A NASA study found some clouds that form on tiny haze particles are not cooling the Earth as much as previously thought. These findings have implications for the ability to predict changes in climate.

Related Articles


Andrew Ackerman, a scientist at NASA Ames Research Center, located in California's Silicon Valley, and his colleagues found, when the air over clouds is dry, polluted clouds hold less water and reflect less solar energy. Ackerman is the study's principal author.

Contrary to expectations, scientists observed polluted, low-lying clouds do not generally hold more water than cleaner clouds. Low clouds cool the planet by reflecting sunlight away from the Earth's surface, and more water makes a cloud more reflective.

Previously, scientific consensus was, that since polluted clouds precipitate less, they should contain more water and reflect more sunlight back into space. Most predictions of global climate change assume less precipitation will result in clouds holding more water, reflecting more sunlight and counteracting greenhouse warming.

"The natural laboratory we used to look at the contrasts between clean and polluted clouds is a phenomenon called ship tracks, which are long lines of clouds with smaller cloud droplets that form on the exhaust particles from ships," Ackerman said.

"The results of this work should provide for more realistic treatment of polluted clouds in climate models, improving predictions of future climate," Ackerman said. "In the meantime, it's critical that we thoroughly test these new theoretical results. NASA's latest generation of Earth-observing satellites provides a powerful tool for doing just that, by observing how ship tracks are affected by the humidity of the air above them," he said.

Ship track measurements were taken off the west coast of the United States from polar-orbiting satellites and aircraft flying through the clouds. The Moderate Resolution Imaging Spectroradiometer (MODIS) Airborne Simulator instrument (comparable to the MODIS instruments on NASA's Terra and Aqua satellites), aboard a NASA ER-2 aircraft flying above the clouds, was also used to gather data. The measurements show cloud water decreases more often than it increases in polluted clouds.

To understand how cloud water changes in polluted clouds, the team of scientists created a 3-D computer model to simulate atmospheric motions and the formation of precipitation by clouds. The researchers tested their model by comparing its predictions with measurements from field projects devoted to characterizing marine stratocumulus clouds.

After verifying that the model reproduced the behavior of real clouds, the scientists asked their computer model how pollution affects clouds. In agreement with previous work, the computer simulations showed, when air over a cloud is humid, cloud water increases in polluted clouds. However, when air over a stratocumulus cloud deck is dry, surprisingly, simulations indicated that water decreased in polluted clouds, consistent with the behavior observed in ship tracks.

Ackerman's co-investigators included Michael Kirkpatrick, University of Tasmania, Hobart, Australia; David Stevens, Lawrence Livermore National Laboratory, Livermore, Calif.; and O. Brian Toon, University of Colorado, Boulder. The researchers' findings appear in today's issue of the journal Nature.

To access a related publication-ready ship track image on the Web, visit:

http://visibleearth.nasa.gov/cgi-bin/viewrecord?25264

For information about NASA and agency programs on the Internet, visit:

http://www.nasa.gov


Story Source:

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


Cite This Page:

NASA/Ames Research Center. "NASA Finds Polluted Clouds Hold Less Moisture And Cool Earth Less." ScienceDaily. ScienceDaily, 6 January 2005. <www.sciencedaily.com/releases/2005/01/050104072650.htm>.
NASA/Ames Research Center. (2005, January 6). NASA Finds Polluted Clouds Hold Less Moisture And Cool Earth Less. ScienceDaily. Retrieved November 28, 2014 from www.sciencedaily.com/releases/2005/01/050104072650.htm
NASA/Ames Research Center. "NASA Finds Polluted Clouds Hold Less Moisture And Cool Earth Less." ScienceDaily. www.sciencedaily.com/releases/2005/01/050104072650.htm (accessed November 28, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Friday, November 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Scientists Find Invisible Space Shield Protecting Earth

Scientists Find Invisible Space Shield Protecting Earth

Newsy (Nov. 27, 2014) — An invisible barrier is keeping dangerous super fast electrons from interfering with our atmosphere, but scientists aren't entirely sure how. Video provided by Newsy
Powered by NewsLook.com
Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Reuters - Innovations Video Online (Nov. 26, 2014) — Innovative recycling project in La Paz separates city waste and converts plastic garbage into school furniture made from 'plastiwood'. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Blu-Ray Discs Getting Second Run As Solar Panels

Blu-Ray Discs Getting Second Run As Solar Panels

Newsy (Nov. 26, 2014) — Researchers at Northwestern University are repurposing Blu-ray movies for better solar panel technology thanks to the discs' internal structures. Video provided by Newsy
Powered by NewsLook.com
Antarctic Sea Ice Mystery Thickens... Literally

Antarctic Sea Ice Mystery Thickens... Literally

Newsy (Nov. 25, 2014) — Antarctic sea ice isn't only expanding, it's thicker than previously thought, and scientists aren't sure exactly why. Video provided by Newsy
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