Storms near the ocean's surface can create hurricanes

"How does a hurricane start?," asked Kelly Minor, 8, a third-grader at Robert Crown School in Wauconda.

The first requirement for a hurricane is that a storm forms near the ocean's surface.

Blake Adler Hamilton, a senior meteorology student at Iowa State University, said there are a few more things are needed to turn a fierce storm into an all-out hurricane.

Temperature, wind speed and distance are key ingredients in the formula for a hurricane.

"You need warm ocean water, 80 degrees Fahrenheit, reaching down to a depth of 150 feet. If the water's colder, it weakens the hurricane."

Wind speed is the next item. "A hurricane has wind speeds greater than 75 miles per hour," Hamilton said. Various factors contribute to the wind force called the Coriolis force to generate the needed environment for the winds to whip up into a dangerous storm.

Meteorologists, people who study weather patterns, use the Saffir-Simpson Hurricane scale to determine the danger level of a storm. The least dangerous level is tropical depression, when winds can rise to 38 miles per hour. A tropical storm is the next category, with winds as strong as 74 miles per hour. Anything above that is a hurricane. Hurricanes have been grouped by categories, with category 1 being the least dangerous and category 5 being the most.

Distance means miles from the Earth's midpoint - the equator. Hurricanes occur in areas that are at least 300 miles from the equator. "They can occur in the Atlantic and Pacific oceans and in the Southern Hemisphere," Hamilton said.

Since these intense storms can overlap and last more than a week, meteorologists give names to hurricanes and tropical cyclones. They generally select female names starting with the first letter of the alphabet and continue to select names in alphabetical order. "In 2005, the year of Katrina, meteorologists went all the way through the English alphabet and because there were so many storms they used letters from the Greek alphabet," he said.

The hurricane and tropical storm season begins in June and ends in late November, so we are now at about the half way mark. The start of the season showed only four major storms through late July.

Check these out

The Grayslake Area Public Library District suggests these titles on hurricanes:

• "Hurricanes," by Gary Jeffrey

• "Hurricanes," by Michael Woods

• "Hurricanes," by Cari Meister

• "Howling Hurricanes," by Julie Richards

• "Do Tornadoes Really Twist?: Questions and Answers About Tornadoes and Hurricanes," by Melvin and Gilda Berger