Experts say the 2010 hurricane season may be one of the worst in U.S. history, possibly even echoing the deadly summer of 2005. Here's a look at why, where and when hurricanes form, and what you can do to be ready for one.

Hurricanes are more than just thunderstorms on steroids — they're angry mobs of thunderstorms on steroids, built from many smaller squalls that team up in the tropics each summer. These meteorological mosh pits are impulsive and violent, but there's a method to their madness: They help control Earth's climate by hauling heat around the planet, moving it out of the tropics and toward the poles.

Lately, though, their workload has been spiraling out of control, with global sea-surface temperatures increasingly reaching record highs. Just last week, the U.S. National Climatic Data Center reported that 2010 is on track to surpass the two warmest years on record, 1998 and 2005, and that June 2010 was the warmest June since 1880. And although hurricanes are just mindless masses of water and wind, the overworked cyclones seem to be taking out more and more of their aggression on human civilization, including one of their favorite targets: the United States.
 
Hurricane formation is a collision of global influences, and any tropical storm is unpredictable even once it's full-grown, forcing forecasters to issue only a "cone of uncertainty" about its upcoming path. But tropical storms in general become much more consistent over time, haunting the same parts of the world year after year. And while weather-tracking technology reduced many of those regions' death tolls in the 20th century, property damage kept soaring along with coastal population densities. Combined with the gradual loss of coastal wetlands that once buffered against cyclones, this means the average hurricane today is far more destructive than 100 years ago. Add in the expected effects of global warming, and the outlook is even worse.
 
The United States isn't the only or even the most cyclone-prone country on Earth, but a string of big ones recently through the populous, energy-rich Gulf Coast — plus the fear of future hits on East Coast hubs like Miami, New York or D.C. — has drawn widespread attention to the country's risks. The Gulf oil spill has also added another wrinkle to the 2010 Atlantic hurricane season, which is already forecast to be one of the worst in years due to record-high ocean temperatures and the emergence of La Niña.
 
Even with vast improvements in hurricane forecasting and preparedness over the past century, recent cyclones such as Hurricane Katrina in 2005 and Typhoon Morakot in 2009 have been tragic reminders of how devastating an expected storm can still be, and how much vigilance is needed to truly be ready for one. Since understanding and appreciating Mother Nature is often a key step toward surviving her, MNN offers the following look at how hurricanes form, when they form, where they go, why they're dangerous, how they're affected by climate change, and what you can do to be safe.

How do hurricanes form?
Hurricanes are huge heat engines that run on warm water, capable of producing roughly 200 times the entire world's electrical generating capacity with rain and cloud formation alone. Their power source is the sun, which heats up tropical sea water all spring to have the engines building and revving themselves by early summer.
 
Up-and-coming cyclones are categorized by their wind speeds and their degree of organization, giving forecasters a way to classify the threats they pose. Tropical cyclone formation is generally divided into the following four steps:

    * Tropical disturbance: a loosely organized system of tropical or subtropical storming that maintains itself for at least 24 hours. Even the largest hurricane was once a humble disturbance.
    * Tropical depression: a tropical disturbance that has tightened into a cyclone and developed a closed loop of circulation. Tropical depressions have a maximum sustained wind speed of 38 mph.
    * Tropical storm: a tropical depression with more concentrated storming near its center and with outer rainfall forming distinct bands. Tropical storms have maximum sustained wind speeds between 39 and 73 mph.
    * Hurricane/typhoon: a tropical storm that has come of age, with tight, powerful cloud rotation and maximum sustained wind speeds of 74 mph or higher. Known as "hurricanes" in the Atlantic and "typhoons" in the Pacific, major tropical cyclones are further classified by strength, from a Category 1 to a Category 5.

The birth of a tropical cyclone begins when warm surface water evaporates, rises, cools and falls back down as rain. This creates a thunderstorm, the building block of hurricanes, and it's this thunderstorm activity that releases stored heat from sea water so it can fuel the growing cyclone. The water has to be at least 80 degrees Fahrenheit and 150 feet deep, but it also must be at least 300 miles away from the equator to glean the right amount of spin from the Coriolis effect.

Once enough heat is being pumped from the sea into the sky, an outside disturbance is still needed to get everything spinning. One of the more common triggers in the Atlantic is something called an "African easterly wave," produced by temperature differences between the Sahara Desert and the Gulf of Guinea. These waves travel west along a path of warm water known as "Hurricane Alley" (pictured), often stirring up a cyclone along the way. In fact, 60 percent of all Atlantic tropical storms begin with such waves from west Africa, as do 85 percent of the basin's major hurricanes, according to the National Oceanic and Atmospheric Administration.
 
By the time a tropical cyclone evolves into a hurricane, most of the storm has organized into rain bands, which are horizontal cloud strips that vacuum up warm water vapor and send it to the sky, where it cools and condenses into rain (see illustration below). But some cool air is sent inward to the storm's point of lowest atmospheric pressure, where it sinks down and can create a deceptively tranquil, cloud-free zone known as the "eye." The eye is separated from the rain bands spiraling around it by the "eye wall," where the storm's winds are strongest.

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