Aerosol actions to the climate and weather;
How do aerosols contribute to climate changes?
Aerosols sources and properties:
- Aerosols are fine, airborne particles, consisting at least in part of solid material.
- The oceans are the major sources of natural aerosols.
- Air sea exchange of particulate matter contributes to the global cycles of carbon, nitrogen and sulfur aerosols, such as dim-ethyl produced by phytoplankton.
- Ocean and sea water salt is transferred to the
atmosphere through air bubbles at sea surface. When the water evaporates, the
salt is left suspended in the atmosphere.
Other sources:
- There are four other sources of aerosols, which are terrestrial biomass burning, volcanic eruptions, windblown dusts from arid and semi arid regions and pollution from industrial emissions.
- Aerosols can be long lived and therefore be distributed over a long distance,
particularly those coming from gases generated by forest fires.
Aerosols properties:
- Bright colored or translucent particles tend to reflect radiation in all directions and back towards space, while darker aerosols can absorb significant amounts of light.
- Pure sulfates and nitrates reflect nearly all radiation they meet with, causing cool of the atmosphere.
- In contrast the black carbon absorbs radiation readily, warming the atmosphere and also shading the surface.
- Organic carbon or brown carbon, which is the organic matter, has an influence on warming the atmosphere that depends on the brightness of underlying ground.
- Dust as an aerosol impacts
radiation to varying degrees, depending on the composition of the minerals that
comprise the dust grains and whether they are coated with black or brown
carbon. Salt particles reflect all the sunlight they encounter.
How aerosols affect climate:
- Aerosols have an important role in the global climate balance, and so they could be factors in climate change.
- Natural variations of aerosols are believed as a significant climate forcing, and factors that alter the Earth's radiation balance and thus tend to cause a global temperature change.
- There are several ways in which humans are
influencing and altering atmospheric aerosols, either the near ground, like
industrial emissions or as high as the lower stratosphere, where the continuous
emitted aircraft play the role of possibly affecting climate.
Aerosol's action in the climate:
- There are two actions of aerosols in the climate; direct action such as scattering of the solar radiation and the absorption and emission of terrestrial radiation.
- The second
is the indirect action like the effects of aerosols on cloud properties as the
heterogeneous chemistry gases may react at the surface or with the aerosols and
change radiation properties.
Greenhouse gases:
- Greenhouse gases have a well known effect on the global radiation balance and surface temperatures.
- There is much confidence in the greenhouse gas component of anticipated climate change during the next years.
- But climate forcing due to aerosols are not well determined yet.
- The aerosol concentrations depend on the wind, the land surface
conditions, such as vegetation cover, sea surface temperature and other climate
factors.
Aerosols and Climate changes:
- Aerosols are one of the factors that contribute in climate changes as some aerosol elements reflect radiations causing cool atmosphere.
- While others absorb radiations, causing warm
atmosphere, and also shading the surface.
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