Meteorology

Meteorology is a science which treats of atmospheric phenomena. When the phenomena are systematically observed in any place, the results may be generalised to give the climate of the place, a knowledge of which is of immense value in deducing the suitability of any country for the support of animal and vegetable life. A less systematic grouping of atmospheric phenomena is indicated by the term weather. This science of weather and climate cannot be considered exact. Of the upper layers of the air we know very little, and changes in the lower ones are dependent, to a great extent, upon local conditions such as proximity of large areas of water, or elevation of the ground. Thus, observations can only lead to the discovery of atmospheric law, when they are made in many places, over a long range of time, and are carefully compared together. Aristotle may be said to have been the first meteorologist, but nothing exact was done till the invention of the thermometer and barometer. In 1817 Humboldt's "isothermal lines" divided the globe into areas of equal temperature, and gave a first idea of the arrangement, of the climates of the earth. This work on the temperature of different localities has been carried on ever since; but not till 1868 was anything definite done with regard to the pressure of the air and the connection between it and the prevailing winds of any locality. Next followed charts of the rainfall of different districts, the connection between it and the prevailing winds and contour of t he districts. being at once seen. Weather maps now occur daily in our newspapers, but they first appeared in 1858 in accordance with a suggestion of Le Verrier's. These weather maps, drawn up in different places, have been of immense practical advantage in enabling storms to be predicted. The study of meteorology may be divided into considerations of the temperature, pressure, humidity, and the electrical state of the air, together with a study of winds and rainfall. Under these chief heads will come, for example, registration of dew-point, description of clouds and thunderstorms, alteration of the position of a compass-needle, connection between magnetic disturbances and solar changes, and occurrence of Auroras or Northern Lights. Meteorology owes much to observations made by H.M.S. Challenger.