Published Tuesday, November 11, 2003 in the San Jose Mercury News

Weather Corner

From compliments to controversial topics, column has made for wonderful five years

Special to the Mercury News

This week marks the five-year anniversary of the Weather Corner, and what a wonderful half-decade it has been for me. When I approached the Mercury News with the idea in 1998, I had no idea how interesting and fun it would be for me some 130 columns later.

As I often tell students: ``Meteorology is the one science that you will use every day.'' That is why there is a Weather Channel on television, and not a Chemistry Channel. And it's also the reason why forums such as this one are important.

The column has allowed me to not only pass along knowledge I have acquired over nearly 30 years but also to learn many new things as well. For example, I never would have imagined finding out about how weather has influenced the arts would be so fascinating and that it would generate so much reader interest.

Over the past five years, there have been a number of columns and topics that really stand out, mostly for positive reasons. In 2002 I posted an online survey that garnered more than 250 responses. From it we all found out that most of the respondents get their weather from the Internet (57 percent), understood what is meant by a ``30 percent chance of rain'' (76 percent) and most mistakenly think that you need a degree to call yourself a meteorologist (80 percent).

The most controversial topics have consistently been about global warming and about contrails, the streaks of smoke and vapor left in the sky by airplanes.

Latest evidence suggests that there has indeed been a warming of the Earth's atmosphere, but the larger question is how much of that warming is the result of human activity as opposed to natural variation. Regarding contrails, there are people who believe that chemicals or other dangerous substances are deliberately released in such jet emissions. While that idea is widely discussed on late-night talk shows, it has never been shown scientifically to have any truth behind it.

And even my mistakes have garnered a considerable response from the readers of the Weather Corner. Earlier this year I mistakenly typed that the speed of light was 186,000 miles per hour, but 22 sharp-eye readers caught my typo and let me know that it is in fact 186,000 miles per second!

I would be remiss if I did not pass along some well-deserved thank-yous to those who have made this column such a success. To the Mercury News, for sticking with the column even during these tough economic times. To my editors, who always manage to make what I think sounds good into something that really does sound good.

And finally, thanks to the loyal readers of Weather Corner, especially to those who have taken the time to send me questions and comments. I am continually amazed by the knowledge of Weather Corner readers and the variety of great topics and questions that I have received.

There is a complete archive of previous columns online at

Thanks, and keep those questions coming.

Q I received information that in Beijing they produce glass panels that are built to withstand pressure in up to Typhoon No. 12 conditions. My question is: Typhoon No. 12 means how many miles per hour?

Mahalo (Hawaiian for ``Thank you!'') Alfred Hradecky - Honolulu

A A Force 12 storm refers to hurricane force or 74 mph or greater winds on the Beaufort scale. The Beaufort scale was developed by Francis Beaufort, a British admiral, in the 19th century as a means of expressing wind conditions relative to sea conditions. For example Force 8, or gale force winds, are 39 to 46 mph and the seas are described as ``moderately high waves of greater length; edges of crests begin to break into spindrift; foam is blown in well-marked streaks.''

A excellent Web site describing the Beaufort scale can be found at

Q Does North America have a weather pattern similar to the monsoon in Eastern Asia? If so, what are their similarities and differences? If not, why not? I live in San Francisco but come from southern China. Mu Xu - San Francisco

A There is a regular monsoon in Arizona and other parts of the Southwest from July through September that accounts for about a third of Arizona's annual rainfall. This occurs when warm, moist air from the Gulf of Mexico is pulled west by high pressure aloft near the panhandle of Texas. Flowing clockwise around the high pressure, the moist air lifts and condenses into clouds and precipitation as it lifts over Arizona's higher terrain.

The term ``monsoon'' originates from the Arabic word mausim, meaning ``season'' or ``wind shift,'' and as such should not be used to refer to the storms but rather to the seasonal wind pattern.

Jan Null, founder of Golden Gate Weather Services, is a retired lead forecaster with the National Weather Service. Send questions to him c/o WeatherCorner, San Jose Mercury News, 750 Ridder Park Drive, San Jose, Calif. 95190. You also can telephone questions at (510) 657-2246, fax them to (510) 315-3015 or e-mail, or fill out a form online at Please indicate in your e-mail what city you live in.