IF A PICTURE IS WORTH a thousand words, a televised report is worth a million. Films of the drought disasters in Ethiopia, the Sudan, Mozambique and other African countries are heart-wrenching. Almost as disturbing are the perceptions of cause and effect that pervade most comments on the situation.

Many experts would have us believe that somehow the people involved bear responsibility for their misfortune. We are repeatedly told that it is the nomads in these parched lands that ruin the environment. They misuse the land, we are told, chop down the trees and allow their animals to overgraze. Thus, the place becomes a desert.

Most of us are left with the impression that the desert is man-made. This misconception is typical of the simple-mindedness of blaming all the ills of the Earth on mankind. If this misconception were simply naive and rather harmless, it would not matter. However, accepting it may be counter-productive, because it has two very dangerous implications:

It suggests that the people that live in the dry parts of the world ruin their environment because they do not understand it. With this assumption goes the perilously arrogant notion that our "consultants," academics and development planners know the desert better than local inhabitants do.

It insinuates that because such "ignorant" and underdeveloped people made the desert, then our new technologies and scientific techniques can surely fix it.

In reality, deserts form in any segment of the land masses of the Earth for one reason alone: scarcity of rain. The term "desert" itself explains all. It came to us from the ancient Egyptian hieroglyph pronounced "tesert," which means abandoned or forsaken.

This idea correctly implied that today's deserts used to be kinder places in which there was life.

Once, there was rain from which sprang abundant vegetation, and which allowed animals and humans to roam the land. Then, the clouds gradually disappeared. These places dried up and were deserted by plants, animals and man. The deserts are where they are not because of some accident of misuse, but because of the rhythmic patterns of global circulation of air masses in the Earth's atmosphere, which are fueled by energy from the sun.

Heating of the air by the sun's rays causes it to rise in the atmosphere. If the air being heated is over an ocean, moisture is wicked up by evaporation. Since the sun's energy is strongest over the equator, tropical storms that form over those oceans tend to contain a lot of water. As the hot, moisture-laden air rises, it cools and the moisture condenses to form clouds. As the clouds continue to climb, their moisture cools into droplets, and beads of rain fall to earth.

Most tropical clouds burst into precipitation near the equator between latitudes 15 degrees north and 15 degrees south. The resulting heavy rains not only account for the lush tropical forests, but they also foreshadow the aridity of the lands lying in higher latitudes. The same air mass that soaked the rain forests is now cool and contains little moisture.

Winds force the cool air downward, and as it circulates back toward the earth's surface the air warms up again. This descending dry air becomes a hot breath blowing across land masses in rainless belts wherein exist some of the world's most arid lands: the Sahara of northern Africa, the Arabian Desert and the Taklimakan Desert of Central Asia. In most of the two belts that girdle the earth between 15 and 30 degrees north and south of the equator, the desert reigns.

Changes in the amount of energy received from the sun, which are related to the 11- year sunspot cycle and the corresponding magnetic activity, constantly shift the boundaries of the desert. These changes cause not only droughts but floods as well.

My own studies of the records of water levels of Lake Nasser behind the Aswan High Dam depict a complete picture: the levels of water were dangerously low in 1973 and 1984 following periods of African droughts in 1968-1971 and 1980-1983. This corresponds with the period of highest sunspot activity. Furthermore, both periods were followed by dangerous floods in 1975 and 1985, at the point of lowest sunspot activity.

This cycle is superimposed on a rhythm enduring 5,000 years to tens of thousands of years -- that of alternating wet and dry climates in the desert, which are related to global changes in the Earth's atmosphere and may be related to the ice ages. In today's African deserts, which straddle the tropics of Cancer and Capricorn, I have encountered bones of animals, ostrich eggshell fragments, as well as human-fashioned hand tools, milling and grinding stones, and pot fragments. Such remains betray the prevalence of milder weather in the past.

The relics are usually arranged as chapters of a book. In successive layers of sediment, they tell the continuous saga of alternating wet and dry climates. For example, in the eastern Sahara, and particularly in the western desert of Egypt, the earliest human habitation sites flourished in a period of rain that prevailed 180,000 to 200,000 years ago. My research team has established that this was followed by a period of scorched dryness.

The next rainy period came about 60,000 years ago, again followed by a dry episode. Then came another wet chapter in the history of the Sahara about 25,000 years ago. Those alarmed by the southward march of the Sahara -- which they say is the result of recent overpopulation -- should know that 20,000 years ago, during the last ice age, the borders of the Sahara were more than 300 miles farther south than they are today. That dry episode left sand dunes so enormous that they are visible in space photographs. The last wet episode persisted from 10,000 to 5,000 years ago, which is the time of initiation of civilization along the banks of the Nile.

The lesson to be learned is that the desert forms when the global circulation pattern of the atmosphere limits the amount of rain. Based on my own observations during a dozen journeys into the Sahara, that desert was born of water and shaped by the wind. Its flat terrain was the result of thousands of years of erosion of rock by running water during rainy climatic episodes. The force of the water dismantled mountains grain by grain, dug wide channels in the plains, and deposited layers of sediment in lakes that formed in the lowest areas.

With the onslaught of dry climates, the wind takes over. It whirls fine particles of the Sahara into the atmosphere, which travel across the Atlantic and descend into the Caribbean, rendering the sunsets of Miami yellow and never red. As dry conditions persist, the wind lifts grains of sand and accumulates them into marching dunes.

Today's misery in the arid lands of Ethiopia and Mozambique is caused by an enduring drought. As sometimes happens, monsoonal rain clouds do not make it to the edges of the African envelope of the monsoons, which cross the continent at about 15 degrees north and south of the equator, where the stricken areas are.

Similarly, persistent drought caused the devastation of the Sahel a decade ago. The problem is that the drought in these lands is not a one-time event; the severe conditions will again prevail in the future.

Knowing all this, what is it that we should do? The answer is not "aid projects" that result in settling of the nomads around overcrowded towns, as happened following the drought in the Sahel. Take the people out of their element, and they will be unable to fully use their skills. Force them to settle in a place other than that of their own choice, and they will sit and wait for you to solve all their problems. Grain will only feed the people today. We must also illuminate a way for them to feed themselves tomorrow.

It is our duty to humanity to use our abilities to lessen the impact of such devastating droughts in the future. We have learned how to deal with most natural disasters in this country. We should also learn and teach others how to do the same in the hostile, arid environment.

First, we should learn that the desert is not the enemy, for no matter how harsh, it contains the seeds of survival of its people. Rain in the geologic past left behind vast areas of arable land that may be hidden by sheets of sand. Some of that rain water seeped through the rock to be stored in giant underground aquifers. Today, we have the means for locating such hidden resources.

NASA's space shuttle is a very useful tool in this regard. In November 1981 a shuttle- borne radar instrument unraveled the terrain beneath the sands in the southern reaches of the western desert of Egypt. In an area that is now bone-dry without a single blade of grass, the radar revealed ancient river courses as wide as the Nile Valley. Nearby a region was selected to drill for water. Eight wells were dug and all brought fresh water from depths between 25 and 250 feet. Today there is an experimental farm that may be the nucleus for a vast agricultural settlement in this parched land.

More recently, in October 1984 the large- format camera developed for NASA by Itek Optical Systems, of which I am vice president for science and technology, obtained high-resolution photographs of Ethiopia, Somalia and Sudan. The photographs clearly show the migration of people from Ethiopia into Somalia and their refugee camps. They showed the best routes to reach such encampments, something that was most difficult to ascertain during the early stages of refugee aid in Ethiopia. And they showed the areas with potential ground-water resources that may be usd during times of need. It is this kind of information that may make a difference in the long-term resolution of drought in Africa.

For this reason, a recommendation was recently made to NASA to refly the large- format camera on a shuttle mission later this year. This "flight for famine" would be dedicated to the acquisition of high-resolution photographs of the drought-stricken areas of Africa.

Second, we should study the ways of desert nomads and try to reinstate, as much as possible, their age-old practices and desert-born wisdom. Nomads roam the land followed by their meager herds not because they are a restless lot. They do so because theirs is the only way of using the scarcest and most inconsistent of resources: rain. In the desert, when it rains, it does so in one small place and not in others. And when the occasional rain clouds return, it rains in some other place. Desert dwellers have developed a remarkable sensitivity to such happenings.

The Bedouin also know when to make their animals stop grazing to preserve the range, because they know that they will have to return to it someday. Arab folktales include numerous examples of the rules on grazing, and even a case of a war between tribes that resulted from a camel that grazed in a protected land. They acquired this wisdom from thousands of years of experience of living in an environment where the only constant is the scarcity of resources.

It is not the fault of the nomads that deserts exist. Neither is it their karma. It is part of the natural environment of the earth and we should study it in this light in order to make parts of it more beneficial to mankind. Let us put aside the blame for "desertification" and direct our attention to doing something that is constructive and that would have lasting benefits.

Third, we should accept the cyclic pattern of mother nature's moods. Let us remember the dream of a pharaoh of Egypt of "seven years of grain, fat and healthy, growing on a single stalk. Behind them sprouted seven ears of grain, shriveled and thin and blasted by the east wind," which Joseph interpreted as seven years of plenty followed by seven years of famine.

The moral of this Biblical story is as relevant today as it was then. Part of the harvest in years of abundance should be stored for the lean years, as is done in the United States. In industry, a lagging output is unprofitable. In agriculture a failed crop can be fatal.

Searching for water and land resources with space-age technology, helping people understand and use the wisdom of nomads, and collecting grain for use in lean years is a tall order. I have no illusions about that. However, we must start somewhere if we are to lessen the impact of droughts upon humanity.

There is one more important human lesson to be learned in coping with drought and famine. We must require the harsh but fruitful policy of making the afflicted people work rather than sit and wait for "manna from heaven."

When human beings are sick and without hope, they quietly become resigned to their fate and await death. Because of physical weaknesses, however, they are rarely in the mood to argue with anyone, and are easily influenced to assume a more positive attitude.

There is nothing more humiliating and spirit-breaking to humans than being herded into refugee camps. While in these encampments, these people should at least be made to work; dig for water if there is nothing else to do. To make them work is to give them mental strength, which gradually translates into physical strength. Above all, work reinstills into them a sorely needed measure of human dignity.

Living with the desert and its changing moods was done for thousands of years. It can be done again, and we have the opportunity to lead the way. However, if we cannot understand the desert, we should not embark on projects of questionable value and should save our aid funds.