Slike strani

the Atlantic border. Cold as con summers are in proportion to those in the East, it appears that the winters are warmer, in still greater proportion.

In the Atlantic States the mean annual temperature diminishes in going northward about one degree for every degree of latitude. This is the general rule in all climates. But the climate of California presents an extraordinary anomaly in this respect. Along the coast, from the mouth of the Columbia river to Monterey, a range of nine degrees of latitude, the mean temperature varies but little—not more than three or four degrees at most; and even this difference does not correspond exactly with the difference of latitude. On the other hand, the interior climate varies indefinitely, every valley having a climate of its own. The summers, however, are generally hotter in the north. One might start from Los Angeles, near the south line of the State, in summer, and travel northward, inland, five or six hundred miles, and find it growing hotter every day; and he might go in a southeasterly course less than half that distance, and arriving at Fort Yuma, on the Colorado, he would find one of the hottest places in the world.

The sudden fluctuations of temperature, incident to the climate of the Atlantic States, are unknown in California. We have none of those angry outbreaks from the northwest, which change summer to winter in a few hours. The sea breeze is chilling enough, especially when it comes in suddenly to reassert its sway, after one of the occasional warm days of summer; but the sea breeze can never bring the thermometer below 52°.

In the summer months there is scarcely any fall of temperature through the night in the coast climate. The early morning is sometimes clear, sometimes cloudy, but always calm. A windy morning in summer is uncommon at San Francisco. A few hours after sunrise the clouds break away and vanish, and the sun shines forth cheerfully and delightfully; not a breath of air is stirring. Towards noon, or a little after, the sea breeze sets in, and the weather is completely changed. From 65° the mercury drops to 53° or 54° long before sunset, and at that point it remains almost motionless till the next morning. This is the order of things in three days out of four in June, July and August.

In the climate of the coast the nights are never uncomfortably warm. The extreme heat at 10 p. M. at San Francisco, for seventeen years, was 76°. The thermometer reached this point on three different nights; on two nights it reach 75°, on four nights 73°, on two nights 72°, and on five nights 70°—making only sixteen evenings in seventeen years when it was warm enough at bed-time to sit out of doors with thin clothing. The warmest morning in seventeen years was 69°. These facts have special interest in relation to sleep.

Though the nights in the interior are not so uniformly cool, yet there are few localities, even in the valleys, where they are too warm for sleeping, even though the day temperature may have reached 100°. This is a remarkable feature of the climate of the Pacific States, and it has an important bearing on the health, vigor, and character of the population.

In the southeastern corner of the State is a section having a climate of its own. It is known as the Colorado desert, and is comparatively barren of vegetation, owing to the small quantity of rain which falls there. The mean temperature at Fort Yuma, though not exactly in the desert, is, in the month of July, upwards of 10G° at noon, and 9CP at 9 p. M. In contrast with this, is the winter climate of Yreka, near the extreme northwest corner of the State, and representing a small alpine section bordering on Oregon. During the stormy weather of January, 1868, when the thermometer at Marysville and other localities in the north was telegraphed as ranging from 25° to 35°, at 8 A. in., the dispatches from Yreka placed it below zero day after day, and sometimes 10D or 12° below.

We will conclude the subject of temperature with a table, represent- ing the mean of the several seasons at a number of prominent points in California, and also farther northward. The first column gives the temperature of the spring months, March, April and May; and so on, the other seasons are arranged. The last column is the mean annual temperature.


There is this difference between the summer in the interior of California and the Atlantic States—that in the former, it is unbroken by

Br The figures for these localities are probably too low.

the showers and storms which in other regions temper the heat and give variety to the climate. From the beginning of June until November the sky is mostly unclouded, and the sun shines out brightly the whole day.


Throughout the entire year, with the exception of the two months, December and January, the prevailing winds of the coast climate are from the west. Even in those two months, the west wind is often predominant. In the winter and spring it is frequently accompanied with showers, but never in the summer and autumn. The true "sea breeze,'1 the great refrigerator of this coast, is free from rain. It is commonly free from mist till June or July. It begins in February, and for about one half of that month comes in gently towards sunset. In March and April it is more frequent and sometimes strong. Its frequency and force increase in May, and in June it is turbulent and seldom absent. In July it reaches its acme of force. In August it is constant, but not quite so violent. In September it is also constant, but much diminished in force. In October it is lighter, and interrupted. In November it is irregular, and it disappears as December approaches.

It might be said that there are no east winds in California. The lofty mountain ranges to the eastward prevent any general current from that quarter. While the duration of the west wind, coming from one eighth of the compass, is upwards of two hundred days in the year at San Francisco, that from the east octant is not over two days. The remaining portion of the year is divided between dry northerly and damp, cloud-bearing southerly winds. Thus, the winds of California appear to belong to three systems:

1. The sea breeze, dependant on inland heat and ocean cold. Though loaded with vapor, it mixes with the warm, dry air of the land, and can produce no rain—the land air drinking up its moisture.

2. The land winds, from the north, which sweep through the entire State in the winter, and are confined to the interior in summer. They are cold in winter and hot in summer, but always dry. Occasionally they come like a sirocco and burn up vegetation. Fruit is sometimes roasted on the trees by the combined influence of the sun and wind. Along the coast the north wind is modified materially by mingling with the ocean air.


3. The south winds, which are warm, and come from the ocean loaded with moisture. They belong to the climate of winter and spring. Coming along the coast line, their direction is modified by the mountain ranges, and they become southeast winds; or by the pressure of the ocean air, making them southwest winds. Mixing with the colder atmosphere as they travel northward, cloud and rain are the result. They are the storm winds of winter, often doing much damage to shipping in the harbor, and prostrating trees in great numbers in the mountains.

The sea breeze, besides controlling the climate of the coast and bay region during nearly the whole year, modifies very much the summer climate of the interior. Wherever there is a depression in the highlands of the coast, it pours in and spreads itself over the heated earth. At the Golden Gate it has a fair sweep, and enters with great force, striking the opposite shore of Alameda county, where its further progress is interrupted by the hills. It is then deflected northward and southward, and following the course of the bay, at San Jose' becomes a northwest, and at Benicia a southwest wind. It continues its course, spreading like a fan into all the valleys that open towards the bay. At points most remote from the inlet, it arrives late in the day. Chilling and unwelcome as it is to the inhabitants of the metropolis, its afternoon visit is hailed as a blessing by those suffering from the sweltering heat of the interior. Within the range of the sea breeze the trees indicate its course, by leaning in the direction towards which it blows. Around the bay, where the winds are strong, the trees sometimes lean so as to rest their branches on the ground; or the branches grow out only on the lee side, giving the tree the appearance of having been cut down through the center—the windward half being removed. Far inland, on the Sacramento river for instance, where the current of air is always gentle, the trunks of the trees incline slightly to the north. In such localities the tree is bent, not by the violence of the wind, but by its constancy, the young branches being always pressed in the one direction during the growing season.

The sea breeze, though often very strong, is never violent enough to do any serious damage; its force is limited. The norther, which is most apt to occur as a prelude to winter, is not sufficiently strong to do much mischief on land, though from its direction, sweeping the harbor, its effect upon the shipping is sometimes disastrous. If the sea breeze had the same direction, the harbor could scarcely be used in the summer months. The storm-wind of winter, varying from southeast to southwest, is often more violent than either; it is the only wind that ever unroofs buildings in the city, a result that may happen once in ten or fifteen years.

Each of these winds has its time of day, so to speak. The sea breeze is invariably at its height at 2 or 3 p. M.; it subsides by sunset or sooner. The southerly storm-wind is apt to rise in the evening and reach its height about 2 or 3 A. M.; it is not, however, very regular in its habits. The norther springs up in the night, is generally at its height early in the morning, and subsides about noon.

Apart from the sea breeze, there is much less wind in California than in the Atlantic States. At San Francisco, and in the ocean climate generally, the wind is not high on more than three or four days in the five months from October to February, the calmest months in the year being November, December and January.


Mining and agriculture, the leading interests of California, are intimately connected with the distribution of rain. Drought on the one hand and flood on the other, are the terrors of a large portion of the people. For these and other reasons, it is proper to dwell at some length on the subject of rain.

In the entire absence of rain during one portion of the year, and its restriction to another portion, California has but one climate. There is this difference, however, between one part and another, that the rain commences sooner and continues later in the north, and that both the quantity of rain and the duration of the rainy season diminish on approaching the southern part of the State, or rather on receding from the mountainous section.

The rain-year of California does not conform to the calendar year, but extends from summer to summer, embracing the latter part of one year and the former part of the year ensuing. The natural division is in July or August—say the first of August. The calendar year fails to represent properly either a dry winter or a rainy one. Thus, the smallest quantity of rain in any one of the seventeen calendar years was 10.50 inches, in 1865, while the climatic year 1850-51 had but 7.12 inches, and 1863-64, 8.49 inches. On the other hand, the calendar year 1860 had but 10.50 inches, or half the average supply, from which it would be inferred that one at least of the two seasons in which it enters was dry. Whereas, by reference to the table, it appears that both of those seasons had the full supply, being a fraction over twenty-one inches. It so transpired that the rain of one season was mainly in the latter part

« PrejšnjaNaprej »