Sunlight reaching the Earth

Howlin

I dont no if this is the right place to ask this question or not

I want to know that over the past number of years, how much less sunlight is reaching the ground because of the fine particles that we are placing into the atmosphere?
Over the past 5, 10 15 or even 50 years, how much sunlight is reaching the ground compaired to the present?

berkeman

The keyword to help you in your searching is "insolation". The wikipedia article is a reasonable introduction, and has some historical data (although it appears to be for the top of the atmosphere, which won't answer your question). There look to be some good references and links at the bottom of the article that may help you out:

http://en.wikipedia.org/wiki/Insolation

.

Evo

This might be what you are looking for.

http://oceanandair.coas.oregonstate....play&pageID=86

klimatos

We only have approximate answers to your question because measurements at the outside of the Earth's atmosphere are relatively short-term (less than thirty years) and measurements at the surface have been made only at a relatively few locations that do not systematically cover the Earth's surface.

Fine particulates can both reflect and absorb sunlight. However, most atmospheric scientists believe that their major significance of such particulates is as cloud condensation nuclei. Such nuclei can increase both cloud cover and cloud density.

There is recent evidence that society's desire to clean up factory emissions has resulted in decreased overall cloud cover.

256bits

Fine particles also are produced naturally from volcanoes, forestfires and dust storms and that can vary from year to year, decade to decade, Sorting out man-made from natural is at most difficult.

Dotini

To the list of fine particles, may it be allowed to include muons?
http://cosmic.lbl.gov/SKliewer/Cosmic_Rays/Muons.htm

Respectfully submitted,
Steve

Evo

Are you making a case that they have a significant effect on sunlight reaching the earth? Do you have any kind of study on this? That might be your answer.

Dotini

Dear Evo,

Thank you for your questions and suggestion.

Firstly and most importantly, I would like to emphasize that I am not making a case of any kind regarding sunlight reaching earth, as it is (a) beyond my ability and station to do so, and (b) treads too near certain proscribed topics which might tend to put undesirable workload on Mentors.

As tactfully as possible, and without comment, I would like to draw the attention of our readers to a pilot experiment of a few years ago: http://www.atmos-chem-phys.org/10/16...1635-2010.html

According to rumblings in the science press, this experiment has very recently reached a conclusion which await release and publication. I have no idea of the results.

Please feel free to delete this post if it's in the best interests of PF to do so. It's no big deal to me, as I'll be kart racing at Spokane for the next couple of days!

Respectfully yours,
Steve

Dotini

http://www.scientificamerican.com/ar...to-cosmic-rays

Now Scientific American, a partner of PF, is making a careful announcement regarding this question.

Respectfully submitted,
Steve