Question: Just what are tradewinds, and how do we tell the difference?

Answer: We found the most understandable and interesting explanation of tradewinds on a home-grown Web site, weather expert Glenn James' hawaiiweathertoday.com.

Click on “;FAQ”; and the second question is “;What are tradewinds, why do they blow in Hawaii and how did they get their name?”;

The simple answer to your question is that cooler tradewinds come from the northeast, as opposed to Kona winds, which come from the opposite direction, bringing muggier weather.

Here's the more educated answer, courtesy of James (we've shortened it somewhat):

A series of rotating air cells circulate air from the warm equatorial regions toward the poles and back.

In the case of Hawaii, warm air rises from the south, near the equator, moving north through the upper atmosphere.

This airflow sinks back to the Earth's surface, then flows back over the islands toward the equator. As it does so, its movement is curved by the earth's rotation, causing it to flow out of the northeast.

These are “;the famous tradewinds felt in Hawaii and other tropical locations.”;

Since the air cells circulate around the globe, tradewinds can be found within the same band of latitude above and below the equator.

As to how they got their name, James said early maritime traders, in the days of wooden sailing ships, relied on tradewinds to cross the oceans to distant lands to trade their goods. “;The wind gets its name then from these traders.”;

We reached James on Maui, where he's the senior weather analyst for the Pacific Disaster Center, working closely with state and county civil defense officials and National Weather Service forecasters.

Until last month he also was the host of a live TV show about the weather. He gave up his TV broadcast after 18 years, burned out working 14-hour days. But, his popular Web page, which he launched in 1996, continues.

James has been on vacation on the mainland since last weekend, so wasn't around to post information about the windy weather that spurred state and city officials to close offices and schools.

In answer to your question about how to tell the difference between trade and Kona winds, one way is that Kona, or southeast winds, are the ones that bring the vog from the Big Island to Maui and Oahu.

“;When winds clock around the dial to south, we call these Kona winds,”; James said. “;'Kona' is a Polynesian word for leeward. So Kona winds come from the opposite direction of the trades and come from the south and west-facing leeward sides. They can be strong and gusty at times and bring warm and muggy conditions to Hawaii.”;

  Another kind of wind, not trade or Kona, comes from the northern latitudes, bringing typically cool and somewhat drier weather, James said.

In Hawaii, tradewinds are much more prevalent during the summer.

“;The tradewinds blow typically 95 percent of the time in June and July and go down to 42 percent in January,”; James said. “;They do go on vacation, so to speak, in the winter.”;

James said he's been captivated by the weather from childhood: “;I was a little boy who grew up into a weatherman.”;

He was teaching physical geography and weather classes at Maui Community College, where he began doing his TV show in 1991. A grant from NASA spurred the creation of his Web page.

Can weather in Hawaii really be described as “;interesting,?”;

“;It is, and it's my job to make it interesting,”; James said.

Such as finding creative ways of looking at the tradewinds blowing - “;giving it perspective from different times of the year. ... If you have a deep interest and deep love for something, you see it in a different way than most people see things.”;

His site has become so well established, it's become No. 1 on the search engines for people looking up weather in Hawaii - both locals and tourists, he said.

  When something's happening with the weather, he said, he'll get 25,000 visits a day; more typically, he gets 7,000 to 8,000.

People wanting to know about the weather, especially those coming on vacation, “;don't necessarily go to the (National Weather Service) page because it's not very humanistic,”; James said. “;For me, I humanize the weather and make it understandable for the lay person.”;

James is always updating his Web page to keep it current.

“;I add pictures several times a day and update it, and I put in new information,”; he said. “;It's a one-man show - that's why it takes so long to do that.”;

What keeps him going are all the e-mails he's received from “;all over the world, from all countries ... tons of positive acknowledgment. That's partly what's kept me going. I love weather, but still, to go with something so long, you need that positive support.”;