Aerosols in the air

Tiny solid and liquid particles 

suspended in the atmosphere 

are called aerosols. 

Windblown dust, sea salts, 

volcanic ash, 

smoke from wildfires, 

and pollution from factories 

are all examples of aerosols. 

Depending upon their 
size, type and location,

aerosols can either cool 

the surface, or warm it. 

They can help clouds to form, 

or they can inhibit cloud formation. 

And if inhaled, some aerosols 

can be harmful to people's health.

The map shows average monthly 

aerosol amounts around the world 

based on observations 

from the Moderate 
Resolution Imaging 
Spectroradiometer (MODIS) 

on NASA's Terra satellite. 

Satellite measurements 
of aerosols, 

called aerosol 
optical thickness, 

are based on the fact 

that the particles 
change the way 

the atmosphere 
reflects and absorbs 
visible and infrared light

An optical thickness 

of less than 0.1 

(palest yellow) 

indicates a crystal clear sky 

with maximum visibility, 

whereas a value of 1 

(reddish brown) 

indicates very hazy conditions.

High aerosol amounts 

are linked to 

different processes 

in different places, 

and times of year. 

High aerosol amounts 

occur over South America 

from July through September. 

This pattern is due 

to land clearing 

and agricultural fires 

that are widespread 

across the Amazon Basin 

and Cerrado regions 

during the dry season. 

Aerosols have a similar 

seasonal pattern 

in Central America 

(March-May), 

central and southern Africa 

(June-September), and 
Southeast Asia

(January-April).

In other cases, however, 

aerosol concentrations 

are not related to fires. 

For example, 

from May 
through August 

each year, 

aerosol amounts 

rise dramatically 

around the 
Arabian Peninsula 

and nearby oceans 

due to dust storms. 

Elevated aerosol amounts 

nestle at the foothills 

of the Himalaya Mountains 

in northern India in some months, 

and linger over eastern China 

for much of the year. 

These elevated aerosol amounts 

are due to man made pollution

-- real pollution, 

not CO2, which is

the staff of life, 
and certainly not 
a pollutant !

The picture below 
shows 2000 to 2010 
average aerosols: