Be very, very careful what you put into that head,
because you will never, ever get it out.
Thomas Cardinal Wolsey (1471-1530)
|General Meteorology FAQ|
Click on the symbol for its explanation.
This FAQ (Frequently Asked Questions) is written by Alistair B. Fraser. It is in response to questions posed over the years by readers of the Bad Meteorology pages. If you have arived on this page without having read those pages or the other Bad Science pages, then what follows, will probably make little sense.Issues discussed below
Although the questions presented here are often ones asked by a specific person, each is chosen to characterize a group of similar questions which have been asked about the topic.
The full moon and frost
The start of seasons
General meteorological questions about:
The full moon and frostQuestion:
While enjoying the beautiful fall colors in the Massachusetts woods with a friend this morning, I happened to mention that we would probably get the first hard frost in a couple of weeks, around the full moon. He was incredulous. He couldnt imagine what the full moon could possibly have to do with frost. I was a bit taken aback by his reaction, having spent some years in rural Maine, where such things are common knowledge. He grew up on Long Island, suburban style. I thought this might have something to do with his weather ignorance. However, the more I thought about it, the more I began to question my own weather knowledge. Where did I get the idea that autumn and winter temperatures have something do to with the moon? Is this perhaps an old wives tale, perpetuated by the Old Farmers Almanac? I used to love reading it when we first moved to Maine.
I suspect that there is a very good correlation between the SEEING of the full moon and the SEEING of frost.
I also suspect that there is no (systematic) correlation between the OCCURRENCE of a full moon and the OCCURRENCE of frost.
There is no good reason (nor as far as I know, evidence) that frost is more or less likely during a full moon. There might be a short-term correlation locally caused by happenstance, but this would vanish with a long record. And if the result were true globally we would all be familiar with it as cloudiness would be pulsating worldwide with the phases of the moon. Yet, the fact that one is most aware of the presence of a full moon on clear nights and clear nights also favor frost does prompt one suspect an origin for the idea. That is, observations of both usually follow from it being clear; which hardly supports the idea that the full moon can cause frost.
Thank you for your enlightening discourse on the old wives tale of flushing rotation. I encountered your site while searching for a reference on heat lightening for one of my fifth graders. In a book he found a reference to lightening caused by cloud ions and by heat. I have been unable to locate any resources for him and any help from you would be greatly appreciated.
What is, unfortunately, called heat lightning is just ordinary lightning seen from too far away for its thunder to be heard. Since such observations have often been made with clear skies overhead, and since hot summer evenings particularly favor this type of observation, there has arisen a popular misconception that the presence of diffuse flashes in the apparent absence of the clouds themselves implies that the lightning is somehow occurring in the atmosphere merely as a result of the heat. It isnt so. The clouds and the ordinary lightning are just a long way away.
The start of seasonsQuestion:
Why do the media insist on declaring an astronomical event like the winter solstice as the official start of winter? There was never an act or measure passed by congress to this affect.
I have wondered about the same issues. I think it comes from the publics delight in being able to assert what they believe to be simple facts. Of course, the news media feed this passion.
But then maybe part of the problem is merely knowing what is meant by winter. It is not a monolithic idea, and it is acceptable for one definition of convenience to be applied in one discipline (say, astronomy) and another in agricultural and a third in meteorology. Further, there are geographic and cultural differences in the application of the word. Certainly, the astronomical convention was a matter of complete irrelevance to me as a child: the first day of winter was the day of the first snowfall (which was usually about Halloween). The last day was when the spring thaw began (around Easter). But then the distinction was clear as my home town averaged about 150 inches of snow each winter and once the snow came, it stayed for the duration. That was in the mountains of Western Canada.
I point that out because the answer is going to be different in Florida, Finland, and France. As such, who cares if Congress did or did not proclaim on the subject; winter does not belong to the U.S.A. Further, it is not obvious to me that there should be any meteorological reason that all four seasons should be equally long. Indeed, at some latitudes, summer may only last for a few weeks. And at other latitudes, there are only two seasons: wet and dry.
I think the problem arises not as much from the astronomical recitations of news wonks being wrong, as it does from their marked irrelvance to the meteorological or agricultural winter experienced by their viewers. But then, much of what is offered on the local news is irrelevant anyway.