Want to keep cool on your deck or in your back yard this summer? 

Today, beating the heat is no, er, sweat. Several ingenious products can now help you linger longer outside in comfort. (Perspiration, it seems, is the mother of invention.)

Many devices use the physical phenomenon of evaporative cooling: When water evaporates, the surrounding air cools because it sheds heat in order to transform that water from a liquid to a gas. It's the same reason a breeze feels nice when you're sweaty.

Here's the scoop on several different products and strategies:

The product: Residential misting systems
How it works: In 1981, two Englishmen were roasting outside in Palm Springs as they watched kids play in the sprinklers. "Why can't we be cool, too?" they wondered. When hanging sprinklers overhead didn't work, they eventually borrowed some air-cooling technology from the poultry industry, and Thousand Palms, Calif.-based MicroCool was born. It was the first company to spurt mist over people to keep them comfortable, relates Bill Anderson, MicroCool's outdoor cooling manager. Now several companies compete in this niche.

MicroCool's system works by pressurizing water to about 1,000 pounds per square inch. The water is then constantly fired through a line of patented nozzles overhead. What happens next is called "flash evaporation": The superfine mist -- "the droplets are like 10 microns -- smaller than a human hair; it's like a fog," Anderson says -- is sprayed out and as it dries, the cool air falls. 

Where you've seen it: MicroCool systems are in the Mirage hotel in Las Vegas, and at Disneyland. The company has outfitted warm-weather homes of Gerald Ford, Bob Hope, Suzanne Somers and Bill Gates. "We’ve done (the late) King Fahd's palace in Saudi Arabia," says Anderson.

Price: A MicroCool high-pressure system (pump, hardware, nozzles, piping) starts at around $3,500. Extra effects -- rolling fog over a garden waterfall, for example -- will cost you more.

The product: Bollard outdoor coolers
How it works: The most unique product of Richardson, Texas-based IntelliCool is its bollard outdoor cooler, which looks a bit like squat aluminum lamppost. Hot air is pulled into the device at the bottom. An external pump pressures water, which comes in through buried pipes, to 1,000 psi, which is then shot across six nozzles to start evaporating. As the air cools, it's scrubbed of any extra moisture via a filter, and pushed out through the top of the "lamppost." 

Where you've seen it: Some restaurants in the Dallas area.

Price: Prices start at $999 and go up to $50,000. "We have one client who put about $60,000 worth of our product into his back yard" in Dallas, says Harris. "From what I understand, he's got a pool and a tennis court and a sports court" and has surrounded those with IntelliCool products.

The product: Misting fans
How it works: Several companies, including IntelliCool, Advanced Misting Systems and Cool-Off, offer a two-pronged product: misters with a breeze. Cool-Off's products use high-pressure pumps and tubing to pressurize water to about 1,000-1,100 psi. That micro-fine spray is then misted from a ceramic nozzle that's set in the center of a wall-mounted fan, explains Dave Shank, Cool-Off's president.

The fan allows for targeted breezes and the hotter it is, the better the pay-off. "If it's 95 (degrees) out in Houston or in New Orleans or Atlanta with typically 70% humidity … we can take it from 95 to 78 or 80, plus the breeze on you," Shank says. Cool-Off's Evening Breeze system, with 14-inch fans, is touted to cool a space about 14 feet by 28 feet, and the Cool Breeze system, with 18-inch fans, can cool an area of up to 16 feet by 35 feet, depending on conditions.

The product was originally for commercial use, but as it got a little cheaper, the company began to realize its appeal to homeowners, Shank says.

Downside: The usual caveats apply about slightly lower effectiveness at higher humidity, though the company says it combats that by varying nozzle diameter in different regions (say, a finer mist in higher-humidity areas). Also, the Dual Breeze model, which can cool up to 500 square feet, requires a nine- or 10-foot ceiling, "or the mist is a little too close to the people," Shank says.

Where you’ve seen it: Restaurants in the Houston area.

Price: The four-fan Evening Breeze package is $2,275 while the Dual Breeze package costs $2,745.

Advanced Misting Systems' Mobile One Z24, a high-pressure misting unit on a movable stand with wheels (the fan can also operate without the mist on), costs $1,795.

The product: Portable air coolers
How it works: Escondido, Calif.-based Port-a-Cool Sales and Rentals sells high-tech versions of the age-old swamp cooler -- though they're not anything that old homesteaders would recognize. A garden hose fills up a reservoir in the bottom. The pump takes the water to the top where it is sprayed over fluted pads. A fan blows air across the pads. The friction of the air moving across the pads heats up that wet air. As the water dries, cooler air results and is pushed out of the machine.

These coolers are worlds more efficient than those old swamp coolers, says director of marketing Don Tennison -- and they cost about 50 cents a day to run, in water and electricity, according to surveys by the company.

Downside: The coolers can be big: Imagine a large-screen TV weighing up to 400 pounds on a stand on your deck. But you can get them in colors to match your patio or pool -- or maybe your favorite sports team. (See below.)

Where you’ve seen it: Some NFL teams, including the Dallas Cowboys, have the machines on the sidelines.

Price: From $729 for a 16-inch, 3-speed machine to $2,999 for a mammoth 48-inch, 2-speed cooler.

Consider smart landscaping, alternative materials
If you're not ready to pay up for an outdoor cooler, you still have plenty of ways to beat the heat, including strategically planting a few trees. According to the California Energy Commission, outdoor plants around a home can drop the temperature in the area by as much as nine degrees, as the water vapor released by plants during photosynthesis cools the air. Just don't plant too many or put them too close to your home, which can trap heat rather than promoting air flow.

You also can reduce surfaces that absorb heat such as gravel and concrete driveways; in the height of summer, a lawn is 10 degrees cooler than plain, bare ground, says the commission. Use bark or woodchips instead of concrete for walkways and consider vinyl decking instead of the usual wood variety. Vinyl planks are cooler for two reasons, according to Jeff Wagner, a product development engineer for manufacturer Thermal Industries: 1) They have channels inside them, which allow heat to dissipate, and 2) they can be made in lighter colors such as white or almond, which reflect much more light than wood or a composite deck of wood and recycled plastic.

On the front end, vinyl costs about four times as much as a wood deck, and three times as much as a composite deck. But in the long run, you'll save time and money by not needing to treat your deck every one or two years with water repellent. Now that's cool.