AT DAWN WE drifted over Lake Manassas. Fifty feet above the water we saw the reflection in the placid water, a manificient hot air balloon, its colors of pink, purple and white catching the morning sun. Suspended from the balloon was a rattan basket carrying two contented passengers.

It was a scense straight from the Land of Oz. Moments later we eased over a boatload of fishermen. They were awestruck, both by the beauty of the balloon and by the dicovery that they could talk to its crew.

"Caught anything?" asked Mike Kohler, the balloon pilot.

"Not yet," came the startled reply. Then, as if responding to a message from on high, a brass struck the fisherman's line.

Such is the magic of ballooning.

The flight lasted a little less than two hours, but the sensations of the trip - of looking down, not up, at tree tops, of spotting a rabbit skitter through a corn field, of waving to pajama-clad families who rushed to their backyards - are long retained.

"It is not," said Kohler, "your everyday kind of experience."

Ballooning is not cheap. A two-hour charter flight costs $100 for one person and $150 for a twosome. The balloon's basket (carriage is the proper term) can accommodate only three adults. And, since Kohler weighs 220 pounds, he likes his twosomes light.

"If one guy weighs 170, the other has to be down near 125," he said. "A man and a woman make nice traveling companions."

It is easier to arrange a charter blloon flight on a weekday than a weekend. Students training to become certified balloon pilots often reserve the weekends. Kohler's course requires 10 hours of flying time and $950.

A little over two years ago, Kohler, now 29, quit his "everyday 9-to-5 job" as a claims representative for an automobile manufacturer and began ballooning for a living. He moved to a farm in Prince William County to divide his time among cattle, horses and balloons.

But balloons get most of his attention. His overalls are decorated with advertisements for the balloons he sells. An intermediate size balloon and carriage go for $6,500, he said. His cap carries the message that he attended the national balloon championships in Indianaola, Iowa.

"When I close my eyes I see balloons," said Maria, Kohler's wife. They were married last April. "We had the reception, a bull roast, at the farm," Kohler said, and the newlyweds left for their honeymoon in a caravan of balloons.

Most balloon trips start early in the morning to avoid "thermals," the winds that rise off the earth when it gets heated by the sun. So it was 6:30 liftoff in our flight plan and the Kohlers were readying the balloon.

Maria unrolled the top of the balloon, or "envelope." Mike checked the propane tanks and lines. A burner heats the air inside the envelope and, since hot air rises, so does the balloon.

In 15 minutes, the evelope billowed over the carriage and Mike simply said "we're ready."

We eased into the sky. The burner made some noise, but there was no deafening roar, no jolt, no flashing sign demanding that we fasten seat belts.

We glided over trees, surprised a sleepy Irish Setter, spied on a garden of giant squash, stared down a bull from the safe distance of 50 feet aloft and played tag with a monarch butterfly. It was intoxicating.

Throughout the flight, Kohler kept an eye out for Maria who was on the ground driving a truck or "chase" vehicle.T"Some guys have a CB radio to keep in touch with their chase," Kohler said. "But to me that is part of ballooning . . . being cut off from the ground.

Kohler pulled a rope that released some of hot air in the balloon. We edged toward a filed.

"This looks like a good place to land," he said. "I think there is a road back to it that the truck can get to."

Quickly we skimmed the tops of trees. An oak loomed ahead.

I prepared for a crash; a loud crash, the limb-splintering, fiery kind of crash that planes have when they hit trees. But this was a balloon, a tranquil craft. Instead of ripping us asunder the tree caught us, then gently deposited us in the middle of the field.

"The trees," Kohler said with a hint of a smile, "are our brakes." CAPTION: Picture, One of the grandest sights around is the start of the annual Preakness week balloon race across the Chesapeake Bay from Sandy Point Park. To sample ballooning costs $100 ($150 for two) for an hour or two flight at Blue Ridge Balloon Port in Bristow, Va. (631-0423) or Club Washington in Alexandria (836-2000).