In New England and the adjacent areas of Canada, showers often bring more than flowers. Rain in this corner of North America can be highly acidic, harming lakes, wildlife, and forests in still-undetermined ways.
Acid rain remains one of America's most perplexing environmental problems. But what comes down as acid, must have gone up somewhere as air pollution - and a growing number of scientists in and out of government are pointing a finger of blame at coal-burning power plants and other man-made sources of sulfur dioxide and nitrogen oxide.
The Reagan administration, until now, has insisted that not enough is known about acid rain to mandate expensive solutions such as smokestack scrubbers on power plants.
But lately they sound as if they are changing their minds. A. Alan Hill, chairman of the President's Council on Environmental Quality, says that ''by August'' some acid-rain cleanup proposals will be made by William Ruckelshaus, head of the Environmental Protection Agency.
The most important recent development on the acid rain front occurred Wednesday, when a research arm of the National Academy of Sciences released a long-awaited report on the causes of the problem. The report concluded that there is a direct link between acid rain and sulfur-dioxide emissions from power plants, factories, and other nonnatural sources. In other words, if pollution from these sources was cut 50 percent in eastern North America, acid deposits would be reduced 50 percent.
On the surface this might seem to be a ''so what?'' finding. But previously scientists have been unwilling to guarantee that a reduction in acid rain would follow a reduction in crucial pollutants.
Many environmentalists charge that Midwest coal-burning power plants, in particular, are causing the acid rain problem. Pollution from these plants, some say, is sucked up into the atmosphere, blown cross-country by prevailing winds, and is washed out of the air by rain over New England and eastern Canada. But the National Academy of Sciences panel says it's still not sure where the worst offenders are.
''If you lower the emissions of a Midwest power plant, you'll get an effect somewhere in the eastern US. But we can't guarantee it will be in the hardest-hit areas, such as the Adirondacks,'' says Jack Calvert, a panel member and scientist at the National Center for Atmospheric Research.
The question of how much responsibility long-range and local sources should bear in reducing acid rain is crucial. Utilities grumble that they're being made the scapegoats.
''If acid rain is causing problems, there is no evidence to indict the utility industry,'' says Robert Beck, a program manager at the Edison Electrical Institute, a utility trade association. ''They haven't really looked at local sources, such as urban [pollution] plumes from East Coast cities.''
But it appears likely that any Reagan administration acid rain proposals would include restrictions for coal-burning power plants. A panel of scientists appointed by the White House Science Office on Monday recommended that ''particularly economically effective'' pollution controls be installed now - intensified coal washing, for example, and use of fuel with lower sulfur content during crucial seasons.
''Prudence would say we should take a few cost-effective steps, even if the science isn't yet complete,'' says a White House science policy analyst.