Cleaning up the clouds. Scientists are finding the global problem of acid rain is more complex than they had thought; and the shifting controversy poses challenges to US policymakers

On a clear day, the view from this peak is enchanting. Below lies Lake Placid. The surrounding Adirondack mountains undulate lyrically into the horizon. Sometimes the towers of Montreal can be seen, 70 miles away.

This is the front line of America's acid rain effort. When the final answers to this puzzling environmental problem are found, they may well come from such a place as Whiteface.

For the last week, Whiteface's summit has been shrouded in the more typical foggy broth of cloud moisture and various industrial pollutants - a fine forecast for the scientists who trek almost daily to the silo-like laboratory on the mountaintop. Day in and day out, they have been poking at the surrounding mists with their probes and collection devices, hoping to make some sense of the airborne contaminants that waft by in cloud droplets.

''There are many questions, but the marbles are gradually falling into place, '' reflects Volcker Mohnen, director of the Atmospheric Sciences Research Center at the State University of New York in Albany, which runs the Whiteface facility.

The past year has seen a explosion of scientific interest in acid rain. All that expertise, however, is not making government regulators' task any simpler. Rather than clarifying the question of how acid rain affects plant and aquatic life, recent evidence suggests that the whole equation is more complex than previously thought.

''The field is moving so fast,'' Dr. Mohnen adds, ''that anyone not involved directly in the science will almost certainly be left behind.''

Some of the new research linking acid rain to forest damage suggests that other pollutants may be involved as well. Yet the drive to curb sulfur-dioxide (SO2) gas from industrial sources - a prime cause of acid rain - appears to have a momentum that would ensure some type of action being taken soon.

Some opponents of prompt action on acid rain go as far as to suggest that the issue is a Trojan horse being used by environmentalists to achieve the broader goal of curbing air pollution in general.

''They don't just want to clean up the rain, but the whole sky,'' says William Brown, director of technological studies at the Hoover Institute, a conservative New York think tank.

Environmentalists insist that the problem won't wait for the scientists. ''Some places are at the breaking point,'' says Michael Oppenheimer of the Environmental Defense Fund. ''They just will not take another generation of stress.''

Today's heated discussion of acid rain has grown from just a whisper 20 years ago, when acid rain was an environmental curiosity rarely discussed outside scientific circles. The term ''acid rain'' itself is a catch phrase to describe a whole range of products - fog, snow, mist, dry particles, as well as rain - that arise from the mixing of SO2 and nitrous-oxide (NOx) emissions in the atmosphere with water to form acids. Scientists call the whole assortment ''acid deposition.''

In whatever form, it is blamed for making lakes sterile and lifeless in Scandinavia, eastern Canada, and the Northeastern US. It has been invoked to explain the poor condition of the Statue of Liberty; it is singled out for turning ancient Greek monuments into soft gypsum; and it is thought to be the cause of $2 billion of corrosion damage a year in the US alone.

The problem is also a major irritant in US-Canadian relations: By Canadian estimates, half of the acid deposition in Canada comes from the burning of fossil fuels in the US; while only 10 percent of the fallout in the US originates in Canada.

''There is only so much we alone can do,'' says Canada's environment minister , Charles Caccia. Canada has embarked on a campaign to slash its SO2 emissions 50 percent by 1990. ''It is long past time for action.''

Nevertheless, US efforts to mitigate the supposed effects of acid rain are barely moving. The Reagan administration opposes any legislative action on acid rain right now; instead, it is about to double funding for federal research. Most of the dozen or so bills floated in Congress this year that deal with the issue have stalled for one reason or another.

For example, in May the House health and environment subcommittee rejected a bill that sought to finance pollution controls with a nationwide tax on electricity.

''No scientists say that Wyoming and Utah and Colorado and Montana are responsible for acid rain in the East,'' says Rep. Morris K. Udall (D) of Arizona of the effort. Nearly all the SO2 pollution in the US comes from 31 Eastern states. ''Why should the West be socked for the cost?''

Three Eastern states took matters into their own hands and tried to force the Environmental Protection Agency (EPA) to impose emissions standards on Midwestern states whose industrial discharges were allegedly contributing heavily to their acid rain problem. That was met with a firm rebuff last week: The EPA refused to take action, saying that not enough was known about the transport of air pollutants to take action yet.

Actually, a gradual reduction in SO2 emissions has been going on for years under the Clean Air Act, which calls for a decrease by the year 2010 to levels advocated by many environmentalists, according to the EPA. But critics say the timetable of the act needs to be speeded up by several decades. Not doing so, they warn, is a blueprint for environmental disaster.

Yet at the same time, the question of just what substances ought be to controlled is becoming less certain.

''SO2 isn't the only game in town anymore,'' asserts Eugene Trisko, a Washington-based environmental lawyer. The link of SO2 emissions to damaged lakes and streams was felt to be fairly well established, but lately some evidence has been cropping up to suggest that here, too, modern science may not know the whole story.

Indeed, scientists studying damaged water systems and forests have been turning their attention to other byproducts of industrial emissions as well: NOx and hydrocarbons, most of which sputters from the tailpipes of automobiles; ozone, which results partly from the interaction of those two kinds of substances; and heavy metals, such as lead, cadmium, and magnesium.

''In other words, you've got the whole periodic table (of chemical elements) going up in a smokestack,'' says Jack Calvert, a meteorologist with the National Center for Atmospheric Research who headed a landmark National Academy of Sciences (NAS) study into acid rain last year. ''What happens to it all? We don't exactly know.''

Scientists are trying to construct theories that describe the complex interactions of these compounds and explain the reasons for forest damage in North America and Europe. But the answers are uncertain.

''If I say to scientists, 'Put your fist on the table and tell me what's responsible for tree decline,' now they invariably say, 'Ozone - but don't quote me, because I can't prove it yet,'' EPA administrator William Ruckelshaus said.

The regulators who have to decide how to control such problems, however, dwell not in the rarified world of scientists such as State University of New York's Mohnen, but in the noisy realm of buraucrats and lawyers, where scientific knowledge is pitted against such pressing questions as ''who pays?'' Such uncertainty puts environmentalists in the difficult position of arguing for programs that, over the course of time, may ring up $300 billion in costs - with uncertain results.

''Do they ever tell you how many lakes and fish will come back to life?'' asks the Hudson Institute's Mr. Brown.

While there are models that try to make such predictions, many environmentalists shy away from displaying them too prominently. They say that if the amount of the man-made SO2 being poured into the atmosphere were halved, significant benefits would almost certainly be obtained. And they point to a considerable body of evidence to support their claim. The Congressional Office of Technology Assessment estimates that a 35 percent decrease in the deposition of sulfate - an acidic form into which SO2 can be changed - would cause some amount of recovery for 14 to 40 percent of damaged lakes and streams in the Northeast.

While some environmentalists acknowledge that other factors may contribute to the damage attributed to acid rain, they argue that for now, SO2 is the pollutant that can most efficiently be controlled.

''You go with what you know,'' says Dr. Oppenheimer. ''Right now, the evidence is in on SO2.''

Environmentalists argue that SO2 is responsible for two-thirds of the unnatural acidity in rain. And logistically, it is easy to control: Of the 27 million tons of SO2 pumped into the air in 1980 by industrial sources in the US, about 80 percent came from 31 Eastern states. About half of that came from the 50 coal-burning plants clustered around the Ohio River Valley. NOx sources are more diffuse: Of the 21 million tons lofted into the air annually, nearly half comes from automobile and truck emissions. So environmentalists want to tighten up some provisions in the 1970 Clean Air Act, which expired in 1982 and is currently up for reauthorization. Under the act, the EPA established ''new-source performance standards,'' sharply limiting emissions of SO2, NOx, and other pollutants from all new fossil-fuel-fired utility boilers built after 1971. Between 1973 and 1982, SO2 emissions from power plants dropped 17 percent, even while coal use by utilities climbed by more than 50 percent. As new plants continue to replace old ones, that figure will continue to drop.

According to some industry and government estimates, it will bottom out somewhere around 14 million tons sometime during the second decade of the next century, before industrial growth sends it creeping back up again.

In the meantime, the EPA also set up ambient-air-quality standards to make sure that emissions from older, uncontrolled plants stayed within reason. The catch was that these standards only monitored air quality on a local scale. So, in order to avoid the installation of costly air-pollution control technology, some utilities dispersed their exhaust through tall smokestacks, which, while taking care of the local pollution problem, released a plume that could stretch hundreds of miles.

Supposedly, that alternative was closed off by the 1977 reauthorization of the act. But the EPA has yet to come up with specific guidelines that say, for instance, when a tall stack is too tall. So in many cases, the tall stacks are still there, poking through a loophole in the Clean Air Act.

''Basically, we want to close that loophole,'' says Steve Howard of the National Wildlife Foundation. Instead of limiting SO2 emissions to so many parts per million in air, they would go directly to the polluting source and place a cap on that output. ''It's a simple extension of a law that is already in place, '' he adds.

But others believe that something else may be at work as well. ''I think there may be a larger agenda surfacing here,'' says Charles Bernabo, who heads the National Acid Precipitation Assessment Program, an umbrella organization that oversees all federal acid rain research. ''They've wanted SO2 reductions for a long time, and now acid rain is the drum they're beating.'

''Put together the words 'acid' and 'rain' and you have a potent emotional slogan that other pollutants just can't match,'' observes Paul Stolpman, director of the EPA office of policy analysis.

Skeptics of current acid rain initiatives concede that the publicity surrounding this issue is heightening public awareness of environmental needs. ''I don't think acid rain is the problem,'' says the Hudson Institute's Mr. Brown, ''But I do think it's good that people want to clean up the air.''

On the other hand, others worry that undue attention may be paid to the SO2 factor, thus limiting the policy debate. ''No one reads the scientific papers,'' Dr. Bernabo argues. ''Too much of the material is being filtered in by special-interest groups.''

That fact gives some observers pause when they consider the price of action.

The costs incurred by the type of legislative initiatives being discussed in Congress transcend just finances. There are social costs, too: Mandated reductions in SO2 emissions could result in fuel-switching - in which utilities replace high-sulfur coal, mined mostly in the East, with the low-sulfur variety found in the West. That would displace coal mining jobs in the East.

On the other hand, installing scrubbers on plant stacks to remove most of the sulfur often requires an initial investment of about $100 million per plant. And it creates an environmental hazard of its own - about 4,000 tons of toxic sulfur sludge a day. On the horizon are emerging technologies that will enable plants to burn high-sulfur coal without the sludge waste, but many industry analysts believe these breakthroughs will not start to have an impact until the turn of the century.

Then there is the issue of the other airborne industrial wastes. ''If we move too fast, we may control the wrong pollutant,'' the EPA's Mr. Ruckelshaus told a House subcommittee last year. Few of the current legislative proposals deal with NOx, for instance. But with hydrocarbons, they can produce ozone, perhaps one of the greatest arboreal antagonists to ride the winds. The link between ozone and damage to crops and trees may be greater than the link with SO2. Some studies indicate that a cut in SO2 alone may actually help boost the rate of ozone production.

Meanwhile, the United States is being pressed to take some kind of action on acid rain. Ten other countries are already grappling to implement newly drafted international standards that recommend 30 percent reductions in SO2 emissions.

''The United States' position on this is very disappointing,'' says Canada's environment minister, Charles Caccia. ''We have research coming out of our ears.''

But there are questions whether the results of that research will ever be certain enough to dictate an enviromental policy. ''Make no mistake - there are major areas of scientific disagreement,'' says Bernabo. ''When will we know enough about acid rain to regulate it? That won't be a scientific but a political decision.''

Indeed, imperfect knowledge has not prevented US regulatory agencies from taking action before. When the EPA formulated lead standards in the early '70s, it had to work with many unknowns.

''In many ways this is a classic case of balancing uncertainties against costs,'' says the EPA's Mr. Stolpman. Regardless of who occupies the Oval Office next year, congressional supporters of acid rain legislation say they are sure some form of controls will be passed soon.

Says Sen. Robert T. Stafford (R) of Vermont, coauthor of a bill to reduce SO2 emissions 10 million tons by 1990: ''With the attention this issue is getting, I think it's an inevitability.''