Seasons And Their Characteristics
( Originally Published Early 1900's )
SUMMER, autumn, winter, and spring seasons, we name them that is, times of the year when general weather conditions differ markedly from other times. But we must be certain that those in whose presence we use these terms live in regions where such seasons occur. For us who live in the northeastern quarter of the United States there is little danger of misunderstanding, but should this quartet of seasons be referred to in the presence of a southern Californian or a native Floridian or one from parts outside our country, as the Dutch East Indies, the Philippines, or eastern Brazil, they would not convey the same meaning to these persons that they do to us. In these intermediate latitudes, where the passing Highs and Lows characterize the changing weather, our conception of the seasons is generally in terms of temperature, while in the regions just cited outside the United States it is based upon variations in rainfall. We usually refer to hot and cold or warm and cool seasons, while in many parts of the equatorial countries such terms as wet and dry decide the seasons.
What are the characteristics of the northern seasons? Summer we recognize as a time when we wear light clothing and when by exposing our bodies to the strong rays of the sun we may acquire a nut-brown coat of tan to display upon proper occasion before our friends as a sign of distinct achievement. We know it to be the time of year when vegetation makes its maximum growth, and when many of our cereals, fruits, and truck-garden products reach maturity and supply us with a welcome harvest. Summer we say is hot; but this is not all. Thunder-showers occur with fair frequency, and refreshing showers unaccompanied by lightning and thunder likewise break the monotony of continuous heat. Periods of excessively hot days extending over two or three weeks alternate with relatively cool spells of somewhat less duration. Stretches of moderate temperature on partly cloudy days link periods of extreme types of weather.
The meteorologist recognizes distinct types of cyclones and anti-cyclones. In certain parts of the country for example, in the States of the middle Mississippi Valley he looks upon the southeast portions of the intensively developed cyclones with suspicion, for here is the birthplace of most tornadoes. Or an anti-cyclone may move toward the southeastern Atlantic coast with a cyclone just back of it and to the northwest. With proper conditions existing over the Atlantic Ocean, the anti-cyclone may stagnate, as they say that is, remain in one area for several days or even more extended periods. Southerly winds upon its western side carry large masses of warm air from southern latitudes to the north, and after a few days such a condition is reflected in the newspapers, which begin to re-port heat prostrations and many discomforts arising out of the hot wave. The wave is broken when the High moves off over the Atlantic, and as the situation is relieved heavy thunder-storms may accompany the break, bringing not only a long-sought cool period but destructive winds and rains. Summer, then, is not necessarily a time of settled weather, as we often think, but easily a season of variations, yet fewer than in spring or autumn.
To many, autumn is the most delightful of all seasons, because its cool, invigorating days are yet warm enough to permit us to go about without extra-heavy clothing, and the vanishing vegetation decorates the landscape with a riot of color such as no other season of the year produces. Autumn is the season of Indian summer, whose charms we have already described. Autumn is the time when we gather the last of the harvests, and if the summer has approached the ideal for crops, the bounteousness of the harvest fills us with good cheer, for we are assured of an abundance of food at moderate prices during the ensuing winter.
Autumn is a transition season between summer and winter, and, because it represents a sort of corridor through which we pass from one season to the other, it possesses some of the elements of both. There is no distinct time marking the ending of the one season and the beginning of the other, so we can never be certain just when summer has left and autumn has be-gun. After we have reached well into autumn, then no doubt remains. The first part of the season has recurrent hot days that remind us of summer, and then again these are interspersed with cool days that tell us it is autumn. Toward the end of the season, excessively cold days suggest the advent of winter, while an occasional return of a delightful balmy day impresses us with the reluctant passing of autumn weather.
As a transition season autumn may prove to be a succession of sunshiny days with moderate temperatures, or it may develop into a period of frequent showers and low temperatures. A combination of both types of weather is not impossible. However, the frequency with which it passes as a season of little rainfall and much sunshine has earned for it a reputation embodying these characteristics and has brought this season into popular favor. An occasional adverse autumn is readily forgotten.
Winter has a reputation as a time of extreme cold, howling winds, and snow. Yet winter is not entirely constituted of such an unpleasant sequence. Many a day the sun shines brightly and the calm, cool air stimulates one's energies and enthusiasm. Winter in many respects reveals greater variations within short distances than any other season. In the Ohio River Valley, for example, some weeks take on more the aspect of spring days than of the characteristic winter in the vicinity of the Great Lakes. In northern Minnesota and the Dakotas days of thawing weather are indeed rare once winter is well under way, while in the Central States thaws are of common occurrence.
Winter is a season marked by extreme variability. Changes in weather happen with unusual rapidity. The contrasts in temperatures between the northerly latitudes and those near the equator seem to create striking pressure differences.
Highs are higher and Lows are lower than in other seasons. This means that winds are strong, and cyclones and anti-cyclones move across the country more rapidly and therefore with greater frequency than at other times of the year. While variety of weather encourages activity among a people and contributes to progress, according to Ellsworth Huntington, yet no doubt there is a happy medium beyond which extremes are destructive rather than constructive. Where winters invite too radical changes we shrink from them and wish they were past. On the other hand, it is not uncommon to hear persons remark that the winter has been a "fine one," exhilarating but not severe, steady but not too cold.
Spring is the poet's season--the season of romance, the time of year when plant life once more sends forth its tender new shoots to revive the drab setting of a long winter, and when migrant birds returning to their favorite playgrounds fill the freshened air with songs of cheer. No matter how cold and wet a particular spring may be, spring always suggests relief from the rigors of a long winter and arrival at the threshold of ever-welcome summer. Yet, spring is a period of great variability in weather, with frequent reminders of winter's cold during its early portion and later suggestions of the oncoming heat waves of summer. Uncertainties of spring even more than those of autumn are reflected in the fall in efficiency of weather fore-casters. The unsettled conditions of the atmosphere, with winter's extremes making their exit in favor of summer's relative stability, presents problems in prognosticating that challenge. the best of forecasters.
While we recognize differences in seasons in terms of temperatures, yet as a time of showers spring is traditional. "April showers bring May flowers" is fairly expressive of what people expect in spring; yet, dry spells which threaten to delay the start of cereal crops are not unknown, and excessive rains which prevent farmers from working in their fields or which rot seed in the soil have made many a spring memorable for its adversity.
We have said that the shift from one season to another is not clearly marked and that no particular date may be assigned to the beginning and end of the seasons. At first such a statement may be a bit startling, for haven't our geographies long recorded the date for the beginning of spring as March 21 or 22, summer as commencing June 21 or 22, autumn making its appearance September 21 or 22 and winter ushering itself in on December 21 or 22? These are merely astronomical dates. They tell us, in a sense, the position of the earth with respect to the sun at these times of the year. On March 21 and September 21 the earth's position is such that the rays of the sun are vertical at the equator, and we then have days with twelve hours each of daylight and darkness. On June 21 or 22 the sun's rays are vertical 231/2° north of the equator. The parallel about the earth in this latitude the ancients named Tropic of Cancer and the time of the year the "summer solstice." The word means "sun stands." They recognized an apparent temporary halting of the sun just before it "started south" again. On December 21–22 the sun's rays are vertical 231/2° south of the equator, over the Tropic of Capricorn. This is the winter solstice for us in the northern hemisphere but the summer solstice for those in the southern hemisphere. Here is an interesting reflection of the origin of a view-point. Had the ancients of the Mediterranean areas who contributed so much to our civilization lived south of the equator, our seasons might have had different names. Since these four points are critical in relation to the earth's revolution about the sun each year, and since the dates associated with them correspond fairly closely with the changes of the seasons, they have come to be recognized as the technical beginning dates of the seasons. However, a little reflection will remind us of the unwisdom of accepting these dates too literally. They are good general guides but by no means accurate.
It is this limitation of the seasons by astronomical dates which makes it difficult for some persons to account, for example, for the discord between them and actual summer or winter. July is hotter than June and usually our hottest month, because the earth does not heat at a rate proportional to its exposure to the advancing vertical rays of the sun. The earth conducts heat slowly and hence, after the cold of winter and coolness of spring, utilizes a good share of the sun's rays in heating itself before it radiates heat to the atmosphere. The atmosphere likewise is cool, and such heat as it receives from the earth is rapidly distributed by convection or other movements. Although the sun begins its return southward after June 21, the length of day and still high angle of its rays contribute much heat to the earth in northerly latitudes, and as a con-sequence the cumulative effect results in the maximum warming in these regions occurring in July or early August.
February as our coldest winter month may be similarly accounted for, except that the process is reversed. Even after the sun starts northward radiation continues and reaches its maximum about a month after the winter solstice.
We hear people remark often about the changes in seasons. They say that the seasons come earlier than they used to, or that the winters are less severe, that we have less snow than formerly, that summers are not as hot as they were. These are interesting impressions because many persons seem to have such assurance of their correctness, when as a matter of fact the data over the years do not bear them out.
Seasons fluctuate somewhat, in some years being a little colder or warmer, snowier or rainier, than the preceding year; but in the long run no permanent change occurs. With seasons as with weather forecasts, the public is inclined to recall the exceptions and forget the normal. A single severe winter with heavy snowfall remaining on the ground for either a brief or for an extended period makes a lasting impression upon many persons. Then, again, the older we grow, the less time some of us spend in the out-of-doors and hence the less contact we have with the weather. As the years roll by, people increase in height beyond that of their childhood days, and what seemed to them as children to be deep snow, up above their knees, now appears but a trace.
Adults forget that their knees were much closer to the ground when they were six or ten years old than they are today, and furthermore that as children they sought out the drifts, which helped to exaggerate impressions beyond what the shallower snows in the level places would have developed.
During the past thirty or forty years tremendous advances have been made in convenience of transportation and in the heating of the home and office. Whereas a few years ago we rode in horse-drawn street-cars, or cable cars, heated at best with a little coal stove at one end of the car and perhaps straw on the floor to help keep one's feet warm, to-day the swiftly moving electrically operated and heated car takes us in comfort to various parts of the city. Only twenty-five years ago the automobile was still a rarity and its use restricted largely to the wealthy. To-day it is within the reach of nearly every purse, and as we step into it on a cold, wet, blustery March day and ride at ease to the shopping district, to school, or to work, we no longer suffer the discomforts of years ago when we walked ten minutes to a street-car, waited on a windy corner five or ten minutes more for the car, and then sat in a chilly atmosphere in our damp or wet clothing for half or three quarters of an hour before reaching our destination. It is no wonder that we think the seasons are changing. In truth they are, to the extent that we are surrounding ourselves with greater comforts and less exposure to the elements.
In spite of such transformations, some still insist that snow remained on the ground longer in years gone by, permitting of the widespread use of sleighs. But consider for a moment the change in the character of our roads. They are paved to-day. In fact, the United States has experienced a revolution in road-building. When the automobile first came into being we pointed to European countries as setting an ideal in good roads for us to emulate. To-day Europe is sending commissions to this country to learn how to build good roads. As the snow falls upon cement or brick highway, a speeding auto whisks it into the air and the wind carries it off into the fields. If a fair breeze blows during a snowfall, the flakes have little opportunity to cling to the smooth surface, and they too are picked up and floated into the ditch or prairie alongside. Snow does not have the opportunity to accumulate as of old. It is not the seasons that change, it is our civilization that changes.
Now and then we experience a heat wave of two or three weeks' duration. We squirm and chafe and complain. As the days follow one an-other without affording us relief, we hear persons say that never before have they had to endure such a spell. The telephone bell in the Weather Bureau office rings with increasing frequency as Jones and Smith and Johnson call in succession to learn how high the thermometer has registered and to inquire whether this heat spell has ever been equaled. Imagine their chagrin when they may be informed that fifteen years ago a similar heat wave visited their region which lasted three days longer, and during which the maximum temperature rose five degrees higher. Sometimes in the face of these facts these same persons will say, "That can't be. I don't recall the equal of this." Our "weather" memory is fickle indeed.
All investigations concerning changes in the characteristics of the seasons lead to the same conclusion namely, that while fluctuations occur every few years, perhaps three or four years apart, or eleven years or thirty-five years, they are only slight and show no inclination to become permanent. In our next chapter we shall give further consideration to climatic changes.
We have suggested that seasons are not alike in all parts of the United States nor on all parts of the earth. In our discussion of the relation between weather and business (Chapter X) we indicate the desirability of adjusting national advertising to differences in seasons. The astronomical division of the year into four parts has fitted the seasonal variations so well in north-eastern United States and northwestern Europe, where the major part of the world's business has been transacted and where perhaps most of the world's financial and political power is centered, that we have fallen readily into the habit of applying the seasonal classification for this region to most other parts of the earth. That may be merely an expression of our egoism. But even within these two vast areas the seasons are by no means identical in character, nor are all four of them easily discernible everywhere. For example, the winters of northern France or of England are not so extended nor so cold as in New York or Wisconsin. The summers in northwestern Europe are not so hot as in northeastern United States, and thunder-storms are exceedingly few. Again, in northeastern Minnesota, . along the shore of Lake Superior, spring is quite abbreviated if not entirely absent, if we think of it in terms of the spring of Illinois or Ohio. Winter persists until well toward April or even at times May, and then with a suddenness almost uncanny the vegetation, which apparently is still in a dormant winter condition, seems to burst from its winter covering and come into full bloom within but a few days' time. A similar phenomenon, still more marked, occurs in Finland and northern Sweden. In those regions March 21 or 22 is far from the opening date of spring. Some of the heaviest snows of the year happen at this time and ice in the lakes shows no signs of breaking up.
More important than these astronomical seasons are the growing and non-growing seasons, for it is during the growing season that we provide ourselves with a food supply to carry us through the non-growing season. Recently a Finnish geographer, Ca jander, suggested a growing season for Finland as the period between the time when the daily temperature averages 41° F. in spring and reaches 32° F. in autumn. He sets the arrival of spring by the first temperature figure and the arrival of autumn by the second. From an economic standpoint this delimitation of the seasons for his part of the world certainly has much to commend it.
Needless to say, the polar regions of the earth have virtually two seasons, winter and summer, or darkness and daylight. Incidentally, it is a matter of interest that while these areas are cold, the coldest spot on the earth does not lie within this territory but at the town of Verkhoyansk in Siberia. Here a temperature of -90.4° F. has been recorded, with an average for January of -60° F. Spring is brief and autumn just a trifle longer. Although these regions are characterized by much snow on the ground, the actual fall of snow in a single year is slight, less than in the Great Lakes region. The depth and extent of covering is due to the continuously low temperatures, which preserve what falls. Much of the precipitation occurs in summer, which season is cloudier than winter. The cloudiness of summer is due in part to evaporation of moisture from the snowy surface and in part to the chilling of the moist air over open leads in the partly frozen seas. The total annual precipitation measured in terms of rainfall ranges from a few inches to not more than fifteen inches. Large portions of the polar regions may be classified as semi-arid.
In equatorial areas near sea-level the seasons show a striking contrast with those of the regions just mentioned. So far as temperature is concerned, it is always summer in the Amazon Valley or in the Congo. In fact, some one has effectively characterized these rainy tropics in the statement that "Night is the winter of the tropics." The range in temperature throughout the year is less than fifteen degrees, and in a few places where the annual range is only two to five degrees the daily range exceeds it. Then what are the seasons of the tropics? They are best signified in terms of precipitation, usually two rainy seasons and two dry. When in March the sun is over the equator, heavy daily rains set in. As the sun moves north of the equator and reaches its farthest north in June, there is a lull or relatively dry season. Again, when the sun crosses the equator in September another rainy season ensues, followed by a drier period when the sun arrives farthest south in December.
Although temperatures are high throughout the year, the maximum rarely exceeds 95° F. As with the lowest temperature on the earth, which one might expect to find in the polar regions but does not, so the highest temperatures are not found at the equator, where one might anticipate, but far from it in the hot deserts. The highest air temperature ever recorded is 136.4° F., observed at Azizia in northern Africa. Until this record was made, Death Valley, California, held the first place with a maximum temperature of 134.1° F.
The recurring rains, nearly every day of the year and so regularly during the rainy seasons that it is said one can "set his watch by the time of occurrence of the daily thunder-storm namely, at 2:00 P.M." might cause one to suspect these localities of having the heaviest rain-fall. However, we must seek the margins of the tropics for extremes. The island of Waialeale in the Hawaiian group is reputed to have the highest rainfall on earth 450 inches annually. This record is subject to challenge, but may yet be proved correct. If so, then it wrests supremacy from that euphonious sounding city Cherrapunji in Assam, whose average is 428 inches annually.
We have not attempted to treat in exhaustive fashion all the types of seasons the world over. We hope enough illustrations have been cited to make clear that the four traditional seasons to which so many of us have been accustomed are really not widespread and that their characteristics are highly localized. The rainy tropics, the hot deserts, the cold Arctic, the high mountains, and the numerous transition areas among these have seasons, but not like those in the northeast-ern part of the United States. The simplicity of a four-season classification, in itself highly desirable, no longer has a world-wide application.
Story Of The Weather:
What Makes The Weather
The Moisture In The Atmosphere
Clouds And The Stories They Tell
Thunderstorms, Tornadoes, And Hurricanes
Forecasting The Weather
Seasons And Their Characteristics
Climate And Man
Weather, Climate, And Business
Read More Articles About: Story Of The Weather