Miami's palms or Chicago's bracing breezes? A duel for '92 World's Fair

America's Sunbelt, which has long challenged the frost belt for jobs, funds, and popularity, has thrown down yet another gauntlet.

Site for the duel: Paris. Cost of the challenge: $3 million and rising. Prize: the right to host the 1992 World's Fair, which could give the city that wins it a $6 billion boost.

Chicago, the frost-belt contender, thought it had the fair in its pocket. After several years' work, the Chicago World's Fair 1992 Corporation submitted its application to the US Department of Commerce in August 1981. The application was approved and forwarded to the Paris-based Bureau of International Expositions (BIE), whose members are the 35 largest nations. Next December, the BIE is to choose between Chicago and Seville, Spain.

Or so Chicago thought. But enter Miami, the Sunbelt contender. Barely a year ago, Miamians decided that a fair designed to celebrate the 500th anniversary of Columbus's voyage to the New World ought to be held in a seaside city with a heavily Hispanic population. By Sept. 1, they had forwarded their counterproposal to the Department of Commerce - all 1,200 pages of it. President Reagan now must choose which city is to represent the US before the BIE in December.

On the face of it, the duel may seem no more than a typical competition between any two cities vying for a single piece of trade. Underneath, however, it has all the marks of a North-South battle of styles.

George Burke, vice-president of Chicago's Fair Corporation, invokes experience. Chicago, after all, hosted the 400th anniversary of Columbus's voyage - the 1893 World's Fair. And its chosen site - 600 downtown acres on the shore of Lake Michigan - will use some land left over from the 1933 World's Fair.

He also notes that Chicago, which he says leads the nation in export trade, is an established center of international (especially European) attention. The theme of the proposed fair, Mr. Burke adds, is ''The Age of Discovery,'' which has many facets. ''Christopher Columbus is one, but only a small part of it,'' he says.

Randy Coleman, president of the 1992 Florida Columbus exposition, disagrees. The Miami theme, he points out, is ''Discovery of the Americas.'' He stresses Columbus's Spanish origin, Miami's Hispanic population of more than 700,000, and its proximity to the Caribbean and Latin American countries. Noting that Miami is served by more airlines than any other city in the world, Mr. Coleman observes that ''we're really the bridge'' between the Americas.

In another distinction of styles, Burke faults Miami for what he calls ''a ludicrous expenditure of public funds'' for the fair application. Miami has so far spent about $1 million - $350,000 of which came from public coffers. ''We wouldn't dream of using taxpayers' funds at this point,'' says the Chicago official. Chicago's application ''cost'' about $2 million. Only $400,000, however, was in cash - and that was raised from private donors. The rest came as in-kind assistance volunteered by local corporations. Burke says that ''world's fairs in the US are basically self-supporting.''

Then, too, there is the question of weather. ''Chicago in October? No way!'' one Miami official was quoted as telling a local audience. The fair, running all summer, naturally will climax on Oct. 12, 1992 - the anniversary of Columbus's landfall in America. By then, Floridians may find Chicago chilly.

But Miami in the dead of summer? ''It's never been 100 degrees in Miami,'' insists Coleman. He admits that ''the humidity gets a little bad in the summer, '' but he speaks of cooling sea breezes and of plans for plenty of shade from fast-growing, semitropical trees.

Even the sites, both of which border on the water, pose a sharp contrast. Chicago would plunk its fair right into its muscular downtown area - and even build a second 180-acre island to match one built for the 1933 fair. Miami has selected a 374-acre site on Virginia Key - a small unpopulated island south of Miami connected by causeways from the mainland to Key Biscayne - which offers distant views of the Miami skyline and would be serviced by special ferries.

But on one point both sides agree. Fairs create much-needed jobs, ranging from construction work to what Burke describes as ''selling funny hats and sweeping up after the elephants.''