Winds that rush down mountain slopes are known the
world over –
the foehn wind of the Alps – the chinook of the Rockies –
the zonda of the Andes.
As moist air is carried up and over a mountain peak by strong winds, cloud is formed and pours over the crest of the mountain like a waterfall – the foehn wall or foehn cloud.
Here again the flier who can read the clouds stays clear.
These are among the spectacular features of the aerial drama –
to which we shall later return. But meanwhile, what of the basic meaning of the clouds – what is their role in the life of the earth?
For us, as living creatures, they are one of the reasons we
are men instead of fishes. As land creatures, we must have water.
Without clouds, all water would remain forever in the sea, from which our early ancestors emerged 300 million years ago.
Without the miracle of clouds and rain, the continents
would have remained barren and uninhabited, and perhaps life would never have evolved beyond the fishes.
III. The Water Cycle
Almost all of the earth’s water is contained in the oceans that encircle the globe – all but a mere three percent.
But to us, inhabitants of the land, that three percent is vital.
It is engaged in a never-ending cycle of exchange: from sea to air – from air to earth – from earth to sea.
Water from the sea is constantly being brought to the land.
There it makes possible the existence of plants and animals.
There, in streams and rivers, it carves and molds the face of the land, cutting valleys, wearing away hills.
Over all the vast surfaces of the ocean, stirred and broken by the wind, molecules of water vapor are escaping into the overlying air.
This occurs everywhere to some extent, but in the warm tropical seas on each side of the Equator – the belt where the Trade Winds blow – the escape of water vapor into the air is tremendous.
The warm, moist air rises; in the cooler air aloft it condenses.
Processions of woolly cumulus clouds are set drift in the trade wind.
The moisture in these clouds may fall as rain and be recondensed several times, but it eventually becomes part of the vast circulation of the upper atmosphere – drifting over the continents – embodied in the clouds that day after day move from horizon to horizon.
Then in a drama of turbulence and change hidden within the heart of the clouds, the water vapor begins to return to the liquid state – begins to drop earthward with increasing momentum.
Rain falls on the earth –
the end of a long journey that began in a tropical sea;
yet in a constantly renewing cycle there is no end, as there is no beginning.
Stage succeeds stage, turning again and again upon itself like a wheel.
Or, in the cold regions, snow –
a deep, soft, sound-absorbing blanket bringing a great quiet to the earth; storing moisture that will be released gradually to the thirsty land.
From the run-off of high ground – from melting snowfields and glaciers,
the water finds its way to the streams:
the noisy hill streams tumbling over rocky beds –
the quietly rolling waters of the valleys and plains –
all to return at last to the sea.
Sometimes the process is marked by the violence of storms sometimes Nature indulges in the wild fury of floods –
But often the cycle brings us nothing more troublesome than a gentle April rain – and always it is in the main a beneficent process,
bringing the continents to life.
IV. Cloud Forms
What of the clouds themselves – the aerial agents of this cosmic process?
Someone has said that without the gift of sight, one could never imagine clouds – their beauty, their ever-changing shapes, their infinite variety of form.
STRATUS
Rolling, swirling along the floor of the air ocean are the lowest clouds of all – fog.
For fog is nothing but a stratus cloud so near the earth that sometimes it touches it.
Fog may shut down quickly over a clear autumn night when
the air over the land loses its heat by rapid evaporation into the open sky.
Such a fog is a shallow one; though we earth-bound mortals grope blindly through it, the tops of tall trees may clear it, and in the morning the sun quickly burns it away.
Fog of a different sort forms when warm sea air rolls in over colder coastal waters and over the land –
shutting down harbors –
grounding planes –
isolating ships at sea with its soft grey swirling mists.
When a fog drifts at a height of a thousand feet or so, forming the aviator’s “ceiling,” it is really a layer cloud called stratus.
As we fly above it, it is a veil through which the earth is seen dimly, like the shallow bottom of a bay when one looks down from an idling skiff.
Or it may stretch away to the plane’s horizon like a monotonous Arctic icefield.
Compared with the high-drifting cirrus wisps and the soaring columns of the cumulus, the stratus clouds are the duller earthlings – coarse-textured clouds formed of large water droplets.
CUMULUS
Most beautiful in the infinite variety of their shapes are the cumulus clouds.
These are also the clouds that generate the most incredible violence known on earth – for beside the power of a tornado or a hurricane even the atomic bomb is insignificant.
The birth of a cumulus cloud is relatively peaceful and simple.
As the earth warms under the morning sun, it heats unevenly.
Invisible columns of warm air begin to rise – from a plowed field, a lake, a town – any area warmer than its surroundings.
The column of rising air contains invisible molecules of water vapor drawn from vegetation, evaporated from the surface of earth or water.
Such warm air can hold quantities of water in the vapor state.
Rising, it cools; at a certain point it can no longer contain its water invisibly; and the white misty substance of a cloud is born.
Broad-winged birds like hawks and eagles find these soaring “thermals” and ride them for hours.
Glider pilots seek them out, locating them by the clouds at their summits.
Polynesian navigators steering across the South Pacific from atoll to atoll, find their way by the cloud rising like a kite from each pinpoint of warm land.
Most cumulus clouds have straight-edge bases, as though evened off by the stroke of a cosmic knife –
but the shaping blade is the altitude that marks a sharp change to cooler temperature –
below this line the air column holds its vapor invisibly –
once above it, all the water molecules blossom, through condensation, into the fabric of a cloud.
In regions of very warm, moist air, the atmosphere is in the power of highly unstable forces.
Then a cumulus cloud puffs up and up to extraordinary heights.
When the tornado of June 9th, 1953, approached the city of Worcester, Mass., observers at MIT reported that the
clouds towered right off the radar screens, which could register only to altitudes of 50,000 feet.
Even higher clouds are known from the true tornado country of the middle west –
70,000-foot giants more than twice as high as Everest.
CIRRUS
Most ethereal and fragile of all are the high-floating wisps of cirrus, drifting just under the stratosphere.
If we could approach them closely in an airplane we would
find them glittering in iridescent splendor like the dust of diamonds.
Up in these substratospheric vaults of sky, from which the
earth looks like the sphere it is,
there is a hard, bitter cold, far below zero, summer and wint
er.
So the cirrus clouds are composed of minute crystals of ice –
the merest specks of substance, so thinly spread through the sky that not more than 2 or 3 occupy a cubic inch of space.
It is the high-riding cirrus that first beholds the sunrise, or in evening holds the light of sunset longest, reflecting back to the dark earth the splendor of a light no longer visible –
the rose and gold, the wine and scarlet of the sun.
The cirrus clouds are the birthplace of the snow,
slowly cascading down to earth in long, curving streaks as the crystals fall behind the swift winds of the upper sky. Halos seen around the sun or moon are the ice crystals of a cirrus veil called cirro-stratus.
Like the lower clouds, cirrus is formed of water vapor that is drawn from the sea and pumped aloft in the swift updrafts
of cumulus clouds – or that rides up an ascending elevator
of warm air slipping over a cold front.
Sometimes cirrus is born of material torn from the top of high cumulus by the strong winds of the upper air – winds that tear off the crests of the clouds as, at sea, a gale blows off the wave crests and sends the spindrift scudding away over the water.
Sweeping curls of cirrus indicate the passage overhead of a rushing current of air, pouring through the sky at a speed of two or three hundred miles an hour. [ … ]
Ed.: Carson ends the script with the story of jet streams, the strongest of all winds, and conjectures that the forces that direct the jet stream will be “found in the far depths of the sky [and] written in the clouds.”
Part Four
Part Four covers the period 1959–1963. During that time Carson was occupied with either writing or defending Silent Spring, which she had initially titled “The Control of Nature” when she began her research in the fall of 1957. It took nearly five years for her to gather evidence, synthesize, and shape the enormous body of scientific literature into a compelling indictment against the flagrant misuse of synthetic chemical pesticides, and the folly of trying to conquer nature.
Included in Part Four are three of Carson’s most important public speeches, as notable for their clarity of language as for their expression of her convictions about both the dangers of pollution and the interconnectedness of life. Attacks on Carson and her work increased after 1962, and she answered her critics with a calm but compelling analysis and unexpected political insight. Carson had attacked the integrity of the scientific establishment, its moral leadership, and its direction of society. She exposed their self-interest as well as their poor science, and defended the public’s right to know the truth.
At the same time as Carson carried out her public crusade she was fighting an even graver private adversary. Diagnosed with an aggressively metastasizing breast cancer in 1961, she defended the earth she loved with an added passion born of knowing that her opportunities to speak out were now limited. Part Four ends with letters to her physician and to her dearest friend.
24
[1959]
Vanishing Americans
CARSON HAD BEEN WORKING on the book that became Silent Spring for nearly two years when the Washington Post published an editorial commenting on a recent National Audubon Society report describing the effects of an unusually harsh winter on migrating birds in the South. Knowing that climate variations explained only a small part of the population decline, Carson wrote exposing the role the widespread use of toxic chemicals played in “silencing the birds.” Her focus on birds offered a good opportunity to gauge the public’s awareness of the pesticide problem.
Her letter, published in the newspaper a week later, provided the first clue that Rachel Carson was studying the subject of synthetic pesticides. She was gratified when the public response to her article testified to an intense interest in the subject.
An added benefit of the publication of Carson’s letter was the support of the Washington Post owner Agnes Meyer and of activist Christine Stevens, president of the Animal Welfare Institute in New York. Both women subsequently became influential advocates of Carson’s work.
YOUR EXCELLENT MARCH 30 EDITORIAL, “Vanishing Americans,” is a timely reminder that in our modern world nothing may be taken for granted – not even the spring songs that herald the return of the birds. Snow, ice and cold, especially when visited upon usually temperate regions, leave destruction behind them, as was clearly brought out in the report of the National Audubon Society you quote.
But although the recent severe winters in the South have taken their toll of bird life, this is not the whole story, nor even the most important part of the story. Such severe winters are by no means rare in the long history of the earth. The natural resilience of birds and other forms of life allows them to take these adverse conditions in their stride and so to recover from temporary reduction of their populations.
It is not so with the second factor, of which you make passing mention – the spraying of poisonous insecticides and herbicides. Unlike climatic variations, spraying is now a continuing and unremitting factor.
During the past 15 years, the use of highly poisonous hydrocarbons and of organic phosphates allied to the nerve gases of chemical warfare has built up from small beginnings to what a noted British ecologist recently called “an amazing rain of death upon the surface of the earth.” Most of these chemicals leave long-persisting residues on vegetation, in soils, and even in the bodies of earthworms and other organisms on which birds depend for food.
The key to the decimation of the robins, which in some parts of the country already amounts to virtual extinction, is their reliance on earthworms as food. The sprayed leaves with their load of poison eventually fall to become part of the leaf litter of the soil; earthworms acquire and store the poisons through feeding on the leaves; the following spring the returning robins feed on the worms. As few as II such earthworms are a lethal dose, a fact confirmed by careful research in Illinois.
The death of the robins is not mere speculation. The leading authority on this problem, Professor George Wallace of Michigan State University, has recently reported that “Dead and dying robins, the latter most often found in a state of violent convulsions, are most common in the spring, when warm rains bring up the earthworms, but birds that survive are apparently sterile or at least experience nearly complete reproductive failure.”
The fact that doses that are sub-lethal may yet induce sterility is one of the most alarming aspects of the problem of insecticides. The evidence on this point, from many highly competent scientists, is too strong to question. It should be weighed by all who use the modern insecticides, or condone their use.
I do not wish to leave the impression that only birds that feed on earthworms are endangered. To quote Professor Wallace briefly: “Tree-top feeders are affected in an entirely different way, by insect shortages, or actual consumption of poisoned insects. [ … ] Birds that forage on trunks and branches are also affected, perhaps mostly by the dormant sprays.” About two-thirds of the bird species that were formerly summer residents in the area under Professor Wallace’s observation have disappeared entirely or are sharply reduced.
To many of us, this sudden silencing of the song of birds, this obliteration of the color and beauty and interest of bird life, is sufficient cause for sharp regret. To those who have never known such rewarding enjoyment of nature, there should yet remain a nagging and insistent question: If this “rain of death” has produced so disastrous an effect on birds, what of other lives, including our own?
25
[1960, 1964]
To Understand Biology/ Preface to Animal Machines
CARSON AGREED TO CONTRIBUTE an introduction for the Animal Welfare Institute’s educational booklet, Humane Biology Projects, which addressed the need for reform of biology instruction in the nation’s high schools. The Institute opposed animal experimentation and worked to change the callous attitude toward systematic cruelty that often accompanied classroom biology projects.
A.W.I.
head Christine Stevens was also instrumental in introducing Carson to the work of British activist Ruth Harrison, whose book Animal Machines exposed the inhumane methods of raising livestock and the deplorable conditions in which they were kept before slaughter. In 1963 Carson wrote the preface to Harrison’s book.
Carson’s ideas about the humane treatment of animals place her fully in the tradition of Albert Schweitzer and his philosophy of the reverence for life. Her contributions to these publications emphasize the unity of all life, and the need to cultivate an emotional response to the living world.
Through the next several years Carson quietly aided the work of Stevens and the Animal Welfare Institute, writing to members of Congress in support of legislation banning the use of certain leg traps and against the inhumane treatment of laboratory animals. But she had to be careful not to draw too much attention to her support for causes that might link her in the public mind with fringe groups and extremists, lest she jeopardize her all-important work concerning the misuse of pesticides. Had this not been a real political consideration, Carson undoubtedly would have been an outspoken advocate of the humane treatment of animals.
To Understand Biology
I LIKE TO DEFINE BIOLOGY as the history of the earth and all its life – past, present, and future. To understand biology is to understand that all life is linked to the earth from which it came; it is to understand that the stream of life, flowing out of the dim past into the uncertain future, is in reality a unified force, though composed of an infinite number and variety of separate lives. The essence of life is lived in freedom. Any concept of biology is not only sterile and profitless, it is distorted and untrue, if it puts its primary focus on unnatural conditions rather than on those vast forces not of man’s making that shape and channel the nature and direction of life.
To the extent that it is ever necessary to put certain questions to nature by placing unnatural restraints upon living creatures or by subjecting them to unnatural conditions or to changes in their bodily structure, this is a task for the mature scientist. It is essential that the beginning student should first become acquainted with the true meaning of his subject through observing the lives of creatures in their true relation to each other and to their environment. To begin by asking him to observe artificial conditions is to create in his mind distorted conceptions and to thwart the development of his natural emotional response to the mysteries of the life stream of which he is a part. Only as a child’s awareness and reverence for the wholeness of life are developed can his humanity to his own kind reach its full development.
Lost Woods: The Discovered Writing of Rachel Carson Page 17