Starting April 1, 1995, I began publishing a 12-month series of articles devoted to Weather and Amateur Astronomy. This month's feature is El Nino, or Why was it so cloudy? and deals with the unusual weather of this past winter and spring, especially in the Western United States, where observing has been unusually difficult to do.
If you represent an astronomy club and would like to publish this series of articles, please contact me personally by EMAIL..or write to Todd Gross, Box 8535, Boston, Ma. 02114.
For those of you who live in Eastern Massachusetts, you can access my weather forecasts via a special Weather Hotline with the astronomer in mind. This number appears at the end of the article.
My Home Page deals with BOTH Weather AND Astronomy, and can be tapped into on the World Wide Web at: http://www.shore.net/~toddg/
Please note, that while I may speak authoritatively, I am just an amateur astronomer, like you, and all the information above reflects my personal opinion(s) only based on my experiences to date.
Thanks!
- Amateur Astronomy buff, and weatherdude.. Todd Gross
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World-wide the weather went bananas again this past winter. From almost no snow in the Northeastern U.S., to storm after storm on the West Coast of the U.S., to harsh winter storms in Europe, there was no doubt about it.. El Nino had returned! Amateur astronomers in the Southwestern U.S. put up with the "seasonal" bad weather over the winter, as they have become accustomed to occasionally dreary winters, but when spring returned, they started asking if the clouds and rain would ever end!
While I am happy to report that for the time being, the big storms have migrated northward to Western Canada, I must tell you that we are not totally out of the pattern that started the stormy cycle in the first place: El Nino. What is El Nino? A friend of mine, Gary Gray, wrote this about it on the Internet "Newsgroup" Ne.weather:
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"El Nino is caused by a breakdown in the trade winds in the equatorial Pacific. Why the trade winds break down is, as yet, unknown. However, we do know that the trade winds (blowing east to west) tend to push the top layer of ocean water, which is the warmest layer, to the west. This means there is a pooling of warm water in the western Pacific and cool (relatively cool... it is still quite warm) in the eastern Pacific. Those are normal conditions. However, when the trades break down warm water is allowed to remain in the eastern Pacific. Because the trade winds break down gradually successive sea surface temperatures will give the appearance that the warm waters are migratory (meaning that the warm water appears to move toward the east). The warm water, in reality, is simply being allowed to "build up" in the east. This is El Nino, a significant increase in sea surface temperatures (SSTs) in the eastern near-equatorial Pacific. The associated weather effects are as follows: Water has a much higher heat capacity than air. Therefore, a warming of only a few degrees in the ocean waters is a huge increase in energy. Therefore, in El Nino events a huge amount of energy is pumped into the southern jet stream (usually there are two - occasionally three - jet streams, the subtropical jet being the "southern" one). This then allows many storms to develop off the west coas of the United States. This is why flooding in California is frequently related to El Ninos. Also, places like Texas can get flooded, like a couple of years ago during El Nino, because the subtropical jet is so strong. Meanwhile, these systems are completely "wound up" (frequently it is a secondary storm from the Gulf of Mexico that takes over as the "wound up" storm) by the time they get to the mid- section of the country. As with most "peaked out" storms, they turn north - this is due to vertical structure. So, they frequently wind up going up the Ohio Valley or Appalachians. Given the couterclockwise spin of storm systems, this pumps warm air up the East Coast of the U.S."
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Weather elsewhere, world-wide gets thrown out of whack as well. Depending on your locale, you either enjoyed a rather mild winter and spring, or one that was unusually stormy. It is unlikely that you had a "typical" winter and spring.
The big question on many amateur astronomer's minds is whether or not El Nino has had it's run, or if it will return this next season. The current long range forecasts are for El Nino to die out only slowly, leaving this winter again open prey to some unusual weather! However, in recent weeks there have been some new signs that this El Nino episode may indeed be ending. Nevertheless, El Nino usually returns every 4-6 years, so even if we are through with the offbeat weather for this year, it will return to a sky near you, in years ahead!
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For those of you who live in Eastern Massachusetts, you can access my weather forecasts via a special Weather Hotline with the astronomer in mind. I discuss the chances of having a night with good transparency/stability, and I even update upcoming astronomical events such as conjunctions between the Moon and planets!
The number is 976-6200, and runs 59c/minute (direct dial from 508 or 617)... so limit your calls to when it is most important, such as before a Star Party!
If you represent an astronomy club and would like to publish this series of articles, please contact me personally by EMAIL..
Thanks!
- Amateur Astronomy buff, and weatherdude.. Todd Gross