Weather Station

More Storms

Cyclones, hurricanes and typhoons
Cyclone, hurricane, typhoon—what's the difference? Nothing, really. Each is a powerful tropical storm that can produce destructive winds of 150 miles per hour or more.

Meteorologists call all large areas of low pressure cyclones. Higher pressure air flows into low pressure areas. If temperature and pressure and humidity are just so, these winds can spin into giant monster storms.

What we call these storms depends upon where they are born. When the huge storms caused by cyclonic winds begin above the warm tropical waters of the Caribbean Sea, they are called hurricanes. If the storms begin above the tropical waters of the Pacific Ocean, they are called typhoons. Tropical storms born in the Indian Ocean are called cyclones.

Tornadoes
Monsoon storms can cause a great deal of wind and rain damage in Arizona. But the most destructive wind of all belongs to the tornado. Arizona rarely gets real tornadoes.

Tornadoes usually occur under the jet stream. The jet stream is found high in the sky—at about 36,000 feet—which is where most jet planes fly. The jet stream is a powerful, fast-moving river of air that is similar to the air current that blasts from your portable hair dryer. Inside this stream air jets along at 150 to 200 miles per hour.

Air moving that fast can act like a big vacuum cleaner. It sucks up huge pockets of air from ground level. Combine that force with the right proportions of heat and moisture and tornadoes could result.

Tornadoes are also called twisters. That's because air from different directions gets sucked up at the same time. When those currents bang together they can cause the air to twist at up to 310 miles per hour. That's faster than even the fastest Indianapolis 500 cars. No "Indy" car has yet reached speeds of 250 miles per hour.

Monsoons
A monsoon and a thunderstorm are not the same thing. The word monsoon actually comes from an Arabic word which means season—in this case, the summer season.

Arizona's monsoon winds blow from the south during the summer months, bringing air loaded with moisture from the Gulf of California and the Gulf of Mexico. Blend that moisture in exactly the right proportions with heat and wind, and the result is a thunderstorm almost every time.

During the rest of the year, winds blow in to Arizona from the west and northwest. Those winds cause different kinds of thunderstorms.

Microbursts
Although Arizona rarely gets twisters, it does get some microbursts. Microbursts can be just as deadly as twisters.

Think of microbursts as air bombs. They're blasts of air that begin high up in the clouds and explode straight down.

Microbursts form when raindrops become so heavy that they force the air they are falling through to fall with them. That air can fall at speeds of 90 miles per hour. Air inside normal storms falls at about 10 miles per hour.

When microbursts hit the ground, they pick up dust and shoot it out and up. The resulting blast pattern looks similar to that which would be caused by an explosion.

Dust Devils
Dust devils look like miniature tornadoes. They actually are very different. Tornado winds begin high up in the clouds. Dust devils begin directly on the ground.

Dust devils occur when patches of ground get very hot. The hot ground causes air directly above to heat up rapidly as well. The heated air then rises. Air currents flow into the bottom of the rising column, bang together, and begin to spin.

The result is a whirling column of hot air that sucks up dust and dirt. Dust devils can grow hundreds of feet tall.

The fastest dust devils spin at about 40 miles per hour. Not even close to tornado speeds. Tornado winds spin at speeds up to 310 miles per hour.