Dew is a deposition of water from the atmosphere upon the surface of the earth in the form of minute globules. During the day the earth both absorbs and emits heat, but after sunset its supply of warmth is cut off, though it still continues to radiate heat into the surrounding space. Grass, flowers, and foliage being good radiators, lose after sunset the heat which has previously been absorbed by them, without receiving any in return, and their temperature consequently falls considerably below that of the atmosphere. From the proximity of these cold substances the particles of vapour in the adjoining air are condensed and deposited upon their surfaces in the form of dew, or of hoar-frost where the temperature of the earth is below freezing.
When the sky is clouded the heat abstracted from the earth's surface by radiation is restored by the clouds, which, being good radiators, send back an equal amount of heat to what they receive; and a balance of temperature being thus maintained between the earth and the surrounding atmosphere, no dew is formed. The deposition of dew is likewise prevented by wind, which carries away the particles of air before the vapour contained in them has been condensed. Horizontal surfaces, and those which are exposed to a wide expanse of sky, receive a greater supply of dew than sheltered or oblique surfaces, where circumstances diminish the amount of radiation. The radiation from the earth's surface is one of those happy provisions for the necessities of living beings with which nature everywhere abounds.
The heavy dews which fall in tropical regions are in the highest degree beneficial to vegetation, which, but for this supply of moisture, would, in countries where scarcely any rain falls for months, be soon scorched and withered. But after the high temperature of the day the ground radiates under these clear skies with great rapidity, the surface is quickly cooled, and the watery vapour, which, from the great daily evaporation, exists in large quantities in the atmosphere, is deposited abundantly. This deposition is more plentiful also on plants, from their greater radiating power; while on hard, bare ground and stones, where it is less wanted, it is comparatively trifling.
In cold climates the earth, being cold and moist the clouds prevent the radiation of heat; the surface is thus preserved warm, and the deposition of dew is, in a great measure, prevented. Research Dew
Frost is the name given to the state of the weather when the temperature is below the freezing-point of water. The intensity of the cold in frost is conveniently indicated by the popular expression so many degrees of frost, which means that the temperature of the atmosphere is so many degrees below the point at which the freezing of water commences.
Frost is often very destructive to vegetation, owing to the fact that water, which is generally the chief constituent of the juices of plants, expands when freezing, and bursts, and thus destroys, the vesicles of the plant. In the same way rain-water, freezing in the crevices of rocks and roads, breaks up their surfaces, and often detaches large fragments.
Hoar-frost is frozen dew. It may either freeze while it is falling, when it is found loosely scattered on the ground; or being deposited as dew in the early part of the night it may freeze during a subsequent part of it, owing to radiation. It is generally seen most profusely in spring and autumn; because at those times, while on clear nights the cold is sufficient to freeze the dew, the days are at the same time sufficiently warm to cause a very considerable quantity of moisture to evaporate into the air.
Generally the term transparent is understood to mean that something is see-through, that is that light can pass through it so that objects beyond are clearly visible - like for example a standard window. The term is also applied to objects which allow the passage of radiant heat, other specific types of radiation or sound waves to pass through them. The opposite of transparent is opaque. Research Transparent
Scorpionidea or Scorpiones is the scorpion order of Arachnida. They have four pairs of lung-books in the mesosoma and the post-anal telson forms a sting. Scorpions are amongst the most hardy of animals, able to survive frozen in ice for three weeks, temperatures over 40 degrees Celsius and withstand two hundred times the amount of radiation (such as the fallout from a nuclear explosion) that kills other animals. Scorpions are deaf and nearly blind, but are very sensitive to earth vibrations and air vibrations, detected through feelers. Research Scorpionidea
A H L Fizeau was a French physicist. He was born in 1819 at Paris and died in 1896. In 1847, working with Jean Foucault, he showed that infraredradiation has the same properties as visible light, that is it is reflected, refracted and is capable of forming interference patterns. Then in 1849 he measured the speed of light using a toothed wheel to interrupt the light. Research A. H. L. Fizeau
Charles Greely Abbot was an American astrophysicist. He was born in 1872 at Wilton, New Hampshire and died in 1973. He carried out research into solar radiation, and devised an apparatus for converting solar energy into power in 1972. Research Charles Abbot
Ralph Nader is an American lawyer and reformer. He was born in 1934. He initiated a campaign on behalf of public safety that gave impetus to the consumer rights movement of the 1960s onwards. His views on defective car design, set out in 'Unsafe at Any Speed' in 1965, led to Federal legislation on safety standards. Nader was also a moving force behind legislation concerning radiation hazards, food packaging, and the use of insecticides. Research Ralph Nader
Levothyroxine sodium is a synthetic crystalline levothyroxine sodium (L-thyroxine). L-thyroxine is the principal hormone secreted by the normal thyroidgland. Chemically, L-thyroxine is designated as L-tyrosine, O- (4-hydroxy-3, 5-diiodophenyl) - 3,5-diiodo -, monosodium salt, hydrate. It is used in replacement or supplemental therapy in patients of any age or state (including pregnancy) with hypothyroidism of any aetiology except transient hypothyroidism during the recovery phase of sub- acute thyroiditis: primary hypothyroidism resulting from thyroid dysfunction, primary atrophy, or partial or total absence of the thyroidgland, or from the effects of surgery, radiation or drugs, with or without the presence of goitre, including sub-clinical hypothyroidism; secondary (pituitary) hypothyroidism; and tertiary (hypothalamic) hypothyroidism. Research Levothyroxine Sodium
Abbreviations
Research Dew
