By ELIZABETH FEIZKHAH

NORTH AMERICA

TORNADO ALLEY
For storm chasers, a nice day is a letdown. Every summer, these meteorological disaster buffs scour the midwestern plains from Texas to North Dakota and from Colorado to Indiana, driving hundreds of kilometers a day in hopes of witnessing a striated barberpole supercell storm, an ice-blender hail core, a laminar-outflow stogie or--best of all--a tornado. Prompted by the success of the movie Twister, half a dozen bad-weather experts have begun advertising storm- chasing safaris. Success isn't guaranteed: most days are spent consulting meteorological data, racing to the next potential hot spot, or visiting tourist sites. Tours cost about $1,800 for two weeks; bookings are already being taken for next year's tornado season, from May to July. All participants must sign a liability waiver.

EUROPE

AMSTERDAM
In 1966, a group of car-hating anarchists persuaded the city to provide bicycles as a public resource: people could pick up a white bike, or witfiets, from the sidewalk so long as they also left it on the sidewalk after use. Only the first half of the idea caught on: before long, there were no white bicycles to be seen. Now Amsterdam is testing a more hardheaded version of the witfiets system. The new white bikes, with a distinctive low-slung design and no removable parts, will be stored in self-locking racks at 15 locations around the city center. To release a bike, users must insert a smart-card "key" and select their destination depot on a computerized map. Rides will be free on lightly used routes and cost $1 on more popular ones; dawdlers' cards will be debited 5[cents] a minute if they are more than half an hour late checking in at their destination.

AVIGNON
When clocks appeared in Europe in the 14th century, they were hailed as marvelous imitations of God's vast clock, the universe. The wealthy few who could afford a portable clock or a watch wanted their timepiece's appearance to reflect its wondrous function. And artisans obliged, housing clocks in tiny castles, celestial globes, crucifixes, ships or statuettes, and adorning them with jewels, paintings and engravings. "Treasures of the Clockmaker's Art," at the 14th century Palace of the Popes, showcases 120 Renaissance clocks and watches, together with some less accurate instruments for measuring time: bells, sundials, hourglasses and almanacs. Through Sept. 27. SOUTH AMERICA

SAO PAULO
"The only difference between me and a madman is that I am not mad," said Salvador Dali. Visitors can test this assertion by visiting "Dali," a major exhibition of the eccentric Surrealist's work at the Art Museum of Sao Paulo's 50th anniversary celebrations. Curated by Robert Descharnes, a friend of the artist for more than 40 years, the show includes a selection of Dali's pensees and photographs of him and his wife Gala, along with paintings, drawings, prints, sculptures and costumes.