It has been estimated by meteorologists that the amount of water condensed upon the surface of the earth in the form of dew amounts to as much as five inches, or about one-seventh of the whole amount of moisture that is evaporated into the air. It will thus be seen that dew performs an important part in supporting vegetation.
The same operation in nature's great workshop that forms the dews of summer creates the frosts of winter. The moisture in cold weather is condensed the same as in warm. When it is condensed at the surface of the earth we have the phenomenon of frost, but when condensed in the upper regions of the atmosphere we have that of snow.
Heat radiation from the earth goes on in winter, which is evidenced by the fact that a thick covering of snow is a great benefit to vegetation as a protection against the injurious effects of frost. The writer has seen flowers blooming abundantly at an altitude of 12,000 feet above the sea-level, protected only by the friendly shelter of a snowbank. In some cases the blooming flowers were in actual contact with the snow. By experiment it has been determined that the earth under a thick coating of snow is usually warmer by nine or ten degrees than the air immediately above the snow covering.
A hailstone is a curious formation of snow and ice, and most of the large hailstones are conglomerate in their composition. They are usually composed of a center of frozen snow, packed tightly and incased in a rim of ice, and upon this rim are irregular crystalline formations jutting out in points at irregular distances. Frequently, however, we find them very symmetrically formed as to outline, and the snow centers are almost without exception round. Hailstones and hailstorms differ in different climates, but they are more pronounced in the torrid than in the temperate zone. Historians give accounts of hailstones of enormous size; the very large hailstones being undoubtedly aggregations of single stones that have been thrown together and congealed in the clouds during their fall to the earth.
It is recorded that on July 4, 1819, hailstones fell at Baconniere measuring fifteen inches in circumference, and very symmetrically formed, with beautiful outline. Hailstones in India are said to be very large--from five to twenty times larger than those in England or America--seldom less than walnuts and often as large as oranges and pumpkins. It is recorded that in 1826, during a hailstorm at Candeish, the stones perforated the roofs of houses like cannon shot, and that a single mass fell that required several days to melt, weighing over 100 pounds. It is further recorded that on May 8, 1832, a conglomerate mass of hailstones fell in Hungary a yard in length and nearly two feet in thickness. Still another instance is recorded of a hailstone having fallen in 1849 of nearly twenty feet in circumference. This hailstone is said to have fallen upon the estate of Mr. Moffat of Ord. We will only ask our readers to listen to one more hailstone story, in which it is related that during the reign of Tippoo, sultan, a hailstone fell as large as an elephant. Undoubtedly one of two things was true regarding this latter story; it was either a very large hailstone or a very small elephant. The historian fails to give the size of the elephant. There is no doubt, however, but that hailstones may adhere and form large masses owing to the violent agitation of the elements that always attends a hailstorm.