Ever see a Santa Claus struggling to keep his whiskers while a tornado tries to empty his sack of goodies?

Ever see a fat lady rolling down the sidewalk like a barrel?

Ever see an IBM building with lifelines across its plaza so pedestrians can hold on for dear life?

Come to Chicago, city of shredded awnings, umbrella-mulcher to the world.

The ill wind in the Windy City blows everybody good -- and hard. Especially in the winter. Fierce blasts straight from the Arctic rocket through the high-rise canyons and make all sorts of improbable sights as commonplace to Chicago as Redskins fans are to Washington.

A stroll downtown on even an average day of winter breezes can seem more like a tour through the Twilight Zone than a walk.

Step outside. The wind is at your back, propelling you forward with the irresistible force of a parental hand shoving a first grader out the door in time for the school bus.

Cross the next intersection. The wind has mysteriously turned at right angles. Now, it's blasting sideways across your decks, so strong that your briefcase ought to be chained to your wrist, courier-with-atomic-secrets-style, to make sure it doesn't take off on a quick flight to the land of Oz.

Another block farther and the enemy is full in your face. Forget the perm and the part. Cheeks sag, lips part. Sound is blotted out.

Plenty of cities around the world are windier. Some say there's a windy city somewhere in Oklahoma, for example. Paul Merzlock, a meteorologist with the National Weather Service at O'Hare Airport, reports that Chicago's average wind speeds are not exceptionally high.

So what? The flukes of human inspiration (locating Chicago here on the 42nd parallel instead of, say, where Miami is), and global geography have combined for a special kind of windiness that no metropolis anywhere holds a candle to.

The Rockies to the west and the Appalachians to the east act like the sides of a continent-sized wind tunnel, helping direct warm air masses north from the Gulf of Mexico and frigid Arctic air south.

Aside from the hills of Michigan's Upper Peninsula, there's hardly anything between here and Santa's workshop taller than a rack of elk antlers to impede the wind. The funnel effect is augmented by the city's position at the southern tip of Lake Michigan. This flat expanse of water, hundreds of miles long from north to south, serves as a kind of Daytona Breezeway.

"Chicago is the battle zone where polar air collides with tropical air all winter long," concedes meteorologist Merzlock.

The highest sustained wind (longer than two minutes' duration) ever recorded here was 87 mph in February 1894. Other sustained winds have reached 47 mph in January 1971; 52 mph in May 1965; and 54 mph in March 1965.

When this kind of breeze flows unchecked in winter, the wind-chill factor combination that gauges apparent cold looks like something retrieved from a black hole in space. Last Christmas Eve, for example, it was 25 below zero (F) and the wind was blowing at a (for Chicago) zephyr-like 25-30 mph. The wind-chill factor: 80 below zero. On Jan. 10, 1982, the wind-chill factor hit a low that remains the record: 81 below zero.

It doesn't take much exposure in conditions like that to produce frostbite. Last winter, Cook County Hospital alone treated 173 cases of frostbite. Other hospitals reported a number of frostbite cases, bruises, even broken limbs from the winds.

Certain corners and intersections around town seem especially vulnerable to buffeting by surprise gusts of 40 mph or so.

The high-rises of the Loop, Merzlock says, act as funnels "that increase wind speed by forcing the same amount of wind that is flowing everywhere else into a narrow space between buildings." Hats and coiffures are the losers. Sometimes, more than that.

Nowhere is this more true than at the corner where the IBM building and the trapezoidal headquarters of the Chicago Sun-Times face each other across the 400 block of North Wabash Avenue -- the most implacable wind tunnel in the city.

Watch what happens when unsuspecting pedestrians heading north on the Wabash Avenue bridge reach the far end of the span:

An invisible wall of air smites them. They bend forward, heading uphill against the Arctic barrier. A foot is lifted. The pedestrian teeters as the torrent of wind snatches at the foot. The same wind tugs at their packages. Now it's trying to lift their hats. Coat hems snap and crackle. Lapels flutter like wings . . . hesitation . . . confusion . . . careful . . . takeoff!

Hat blasts away. Package string parts with a pop. Parcels tumble, then leap away. A frantic lunge for the IBM lifelines . . . remember that teetering foot . . . careful . . . thump!

Not everyone blames bruises or nature for Chicago's best-known epithet. Columnist Mike Royko, for example, says a late 19th century writer "came here and wrote about Chicago and took note of the tendency of prominent Chicagoans to be braggarts. It has nothing to do with the weather. It stuck."