Satellite images reveal that clouds affect the particles surrounding them

Oct 18, 2012
Satellite images reveal that clouds affect the particles surrounding them
The sky can appear nearly clear or somewhat hazy between clouds. Now, scientists have found that clouds influence tiny particles near them to attract and hold water, which ultimately affects the balance of sunlight energy between the sun and the Earth's surface. Credit: MayaSimFan

(Phys.org)—Call them cloud wannabes. Scientists at Pacific Northwest National Laboratory found that when the sky is described as partly cloudy, particles near those clouds swell larger with water vapor. The larger particles then reflect and scatter more sunlight energy, like cloud hopefuls. Scientists gleaned these cloud effect secrets from satellite data to find an increase of about 25 percent in the particles' reflectivity.  

Aerosols are of dust, ash, pollution, and suspended in the atmosphere. These small particles have huge impacts on the warming and cooling of the Earth through their power to absorb, reflect, or from the sun. Previously, have neglected the influence of clouds to increase the water attraction by these particles. This research helps scientists better understand some of the effects that have a major impact on how and when energy from the sun affects the Earth's climate.

The PNNL scientists used 11 years of high-resolution daily observations from the (NASA) Moderate Resolution Imaging Spectroradiometer (MODIS) satellites to assess the effect of clouds on aerosols. They analyzed data on the aerosol optical thickness and fraction of the sky covered by clouds using probability density function, a statistical approach that shows the distribution of random variables. This approach enabled them to describe the relative frequency of clear sky to a sky thick with aerosol particle activity in global regions.

A large plume of dust, blowing off the coast of Africa overlaps and mixes with scattered clouds over the Atlantic Ocean. Dust is one type of aerosol particle that can be influenced by clouds to affect the warming and cooling of Earth. Credit: NASA

Although there are various factors controlling the aerosols near clouds, in their analysis the team found that hygroscopicity—the ability of the particle to attract and hold water-is a major factor driving the optical depth of particles. Satellite observations suggest that complex interactions occur between coexisting clouds and . This study will help improve representations of clouds in climate change, and result in a better grasp of how aerosols affect the warming and cooling effect of the sun's energy on the Earth.

PNNL researchers will use the global-scale observations for estimating how and when energy from the sun affects the Earth's climate, which will provide a better understanding of climate models.

Explore further: Methane is leaking from permafrost offshore Siberia

More information: Chand D, et al. 2012. "Aerosol Optical Depth Increase in Partly Cloudy Conditions." Journal of Geophysical Research 117:D17207. DOI:10.1029/2012JD017894

add to favorites email to friend print save as pdf

Related Stories

Down-and-dirty details of climate modeling

May 04, 2011

For the first time, researchers have developed a comprehensive approach to look at aerosols—those fine particles found in pollution—and their effect on clouds and climate. Scientists from Pacific ...

The birth of a cloud droplet

Oct 31, 2011

(PhysOrg.com) -- Wrapped in mystery, the formation of a cloud droplet comes down to physics. Pacific Northwest National Laboratory led a research team that has helped peel away another layer of the cloud droplet ...

Connecting the dots on aerosol details

Jul 27, 2011

Predicting future climate change hangs on understanding aerosols, considered the fine details in the atmosphere. Researchers at Pacific Northwest National Laboratory and the National Center for Atmospheric ...

Recommended for you

Methane is leaking from permafrost offshore Siberia

13 hours ago

Yamal Peninsula in Siberia has recently become world famous. Spectacular sinkholes, appeared as out of nowhere in the permafrost of the area, sparking the speculations of significant release of greenhouse ...

New discovery in Arctic is a very old clam

14 hours ago

The rapidly thawing Arctic Ocean may be a new frontier but some of the latest news from there concerns a clam that is believed to date back more than a million years.

Barren deserts can host complex ecosystems in their soils

14 hours ago

"Biological soil crusts" don't look like much. In fact, people often trample right over these dark, or green-tinted, sometimes raised patches in the desert soil. But these scruffy stretches can house delicate ...

Researchers on expedition to solve 'small island problem'

14 hours ago

Researchers from the Department of Electronic & Electrical Engineering are starting their new year with an expedition to the island of South Georgia to carry out research into improving weather forecasting. You can follow the team's progress on their blog. ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.