Lost Woods (21 page)

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 winter.

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.”

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?