Warning!! Scientific over-achievers may find this boring, imprecise or both.
Regular folks may want to skip to the last paragraph, immediately, or when you get saturated.
By Rob Watson
Disclaimer: I have borrowed this title from wattsupwiththat science blog on the internet. You can get more detailed information from there and Google searches. The information below comes from my memory. Conclusions may be classified somewhere between "educated Scientific guess" and "Wild eyed speculation".
As an introduction, Many WUWT contributors and commentors forget (or ignore) that most of us followers of that blog have less than 60 college hours in Science classes. While I have more, the grades were almost all "C's" except for one Physics, one Chemistry, one Botany and two Geology classes. (These were "A's"... also got an A in "Physics for Elementary Teachers" but that hardly counts) The following is aimed at making sense of entries by the scientific over-achievers in that blog.
Sometime in the '90's some college students were examining spectral lines (Bright lines made by glowing chemicals, when the light from those chemicals are passed through a prism... chemicals on the sun's surface tend to glow) from sunspots on the sun. A followup study revealed that some of these lines were getting dimmer. This lead to a serious study of those spectral lines. The study showed these lines were indeed diminishing. A forward projection of the rate of decline showed these spectral lines indicated they would be entirely gone by 2015 or so. Then came the bad news. Further study showed when these spectral lines were bright the solar activity was high. When they were dim the solar activity was low. or simply: Bright lines hot sun, dim lines cooler sun. Science based speculation extends this evidence to guesstimate that a repeat in the "Little Ice Age" is upon us.
The sun directs about 1,350 watts of visible light to the earth surface (per square yard/meter per second of time) when directly overhead. As the earth is nearly a sphere, time of day and latitude (Distance away from the tropics) diminish this number. That is slightly less energy than you get from an 1500 watt electric heater. In the northern hemisphere, the difference in solar energy between summer and winter averages about 150 watts per second or so (again depending on time and latitude). The difference between hotter and cooler sun is two or three watts per second. {{You can experiment: Take a radiant electric heater outside about noon Local time (no wind). Lay in full sun for a minute. Stand in full shade for a minute. Turn on heater and stand 3 feet from it for a minute. If the heater has a 1200 watt setting try that. Don't forget to record results.}}
In addition, some research shows a cooler sun has a weaker magnetic field. This allows more cosmic rays from outside the solar system to strike the earth causing more clouds and cooler earth. (clouds reflect some of the sun's energy back into space before it warms the earth.) (yes, they also reflect outgoing energy back down... less incoming, less outgoing). Also, particulate pollution (smoke, dust, volcanos) cause clouds and reflect sun energy... remember, less in, less out. Evaporation rate studies show refectance can range from 10% to 30% in some conditions.
And more: Sea surface temperatures also affect land temperatures. Warm Pacific= El Nino, cool Pacific=La Nina. (for reasons that entirely escape me, oceanographers think sea SURFACE temperatures extend down to 700 feet, or is it meters?) For reference purposes, the last 12 months, July 2010 to July 2011, have been classified as a La Nina year. Warm Sun warm Pacific El Nino. Cool sun cool Pacific La Nina.
A classic La Nina draws a line around the northern hemisphere at about the 40 degree latitude line. Above the line, cold wet/snow winters, stormy summers with heat. Below the line, hot dry summers, cold dry winters. La Ninas are also associated with low solar activity... few sun spots.
Because of the elliptical orbit of the earth around the sun, the Earth (and northern hemisphere) is closest to the sun on January 6 or so giving warmer winters north and warmer summers in the southern hemisphere. This gradually changes to colder winter north and cooler summers south. The Earth also varies its tilt on its axis having a similar result. Sometimes they happen at the same time. This requires more research... could I get a grant?
Mostly agreed upon facts: Temperatures during our time, "Recorded History" have been remarkably stable when compared to the last 600,000 years or so. The advance of continental glaciers during the last several ice ages stopped about the 40 degree latitude. (give or take). The last several warm periods, between ice ages lasted about 10,000 years. Our current warm period is about 12,000 years old. Glacial periods last about 90,000 years. Between 1645 and 1715 there were very few observable sunspots, (ie, low solar activity) This period is sometimes referred to as "The little Ice Age"
Four possibilities: 1. The weather for the next year will be like the last year. 2. The weather for the next 75 years will have a new normal, of which last year is the best example. 3. A new Ice age is about to commence and we will get to see the beginnings, with last year's weather being greatly longed for. 4. What I have been smoking is not what I think I have been smoking.
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