CLIMATE

—It has been known from the earliest times that the atmospheric conditions in different parts of the earth are not the same, and the earth was early divided into zones or belts, each distinguished by certain conditions of temperature, moisture, etc., occupying a particular position with reference to the sun. But when the daily, annual, and monthly variations in the atmosphere are considered these divisions are not satisfactory, for local physical features, mountains, locks, etc., become important. It has been found that each place has a certain series of atmospheric conditions each of which is termed the weather. The average weather is termed the climate and the study of weather conditions climatology. The facts regarding weather are mostly derived from ‘atmosphere, Climatology expre es meteorological data in simpler language so that its facts can be utilized by the farmer, planter, and breeder. Crops, industry, and health depend on climate, and therefore a study of its variations is important.; Climatology records the temperature, moisture, pre ure, winds, and evaporation which occur, and considers the regular and irregular variations from the average conditions. The maximum and minimum temperatures, the rainfalls, the frequency, direction, and velocity of winds and the probability of occurrence of any condition are all important matters to agriculturists. The relationships between climate and plants are being most minutely worked out so that the climate can be deducted from the ti ues of plants as these show modifications which enable them to withstand heat, cold, drought, ice, and water. Certain diseases are known to be a ociated with particular weather conditions because certain insects and parasites flourish in these conditions. If the local physical features are altered by drainage the disease vanishes. Three chief varieties of climate are recognized: Marine or Oceanic, where the land warms readily and cools readily. The water warms slowly and little, but does not cool easily, This retards the maximum and minimum changes, giving a cool spring, warm autumn, and only slight seasonal changes. The water thus acts as a source of warmth in the winter months. Abundant evaporation from the surface of the ocean causes higher humidity, larger amount of cloudine , with a heavier rainfall than is found on continents. Climate is equable, damp and cloudy. The air is cleaner and purer and moves more rapidly than over continents. Desert climate may be regarded as a type of severe continental climate. High winds are common by day, but the nights are calm and cold. Occasional downpours of rain occur on the borders of the desert and may cause flooding. The exce ive range of temperature causes the rocks to split up. The wind storms drive the sand against them, and the continual friction polishes them. The plants of the region are peculiarly suited to its climate, having a greatly reduced leaf surface, hairs, very thick skin coated with wax, and various other devices to prevent evaporation. There are several other recognized types of climate. Coast climate is intermediate between ocean and continental. The prevailing winds have a very important effect in controlling it. If they come from the ocean the climate inclines toward the ocean type; if from the shore it is a modification of the continental. There are three seasons in the Monsoon climate—one hot, one cold, one wet, during the summer monsoon. In India the winter monsoon blows off shore, the summer one on shore, A monsoon climate also occurs in Eastern Asia. In a Mountain or Plateau type of climate the height and obstructive effect of the mountains are very important modifying factors. There is a decreased temperature and humidity, and the wind velocity is higher than on the continent. The air is cleaner, purer, and drier. The night temperature is warm because the cold air collects in the valleys below. Uniformity of climatic features distinguishes the Torrid Zone. There are no seasons. Life is regulated by the rainfall. There is a high uniform temperature. Periodic phenomena depending on the daily and annual march of the sun predominate, Cyclones are the only events which have an important economic result, for the destruction they work often takes years to repair. They are restricted to certain regions and special times. The Temperate Zone is characterized by marked changeablene of weather. The mean temperature and hysiological effects are intermediate Getnban those of the Torrid and Polar Zones. The weather changes are apparently irregular and haphazard, but they occur fairly systematically. The winds are the important controls. The seasons are Cla ified by temperature. Except the rather meagre data brought back by recent Arctic and Antarctic expeditions, there is no account of Polar climate. It may be said that the temperate regions have provided the most highly developed human societies, probably because the climate has required a more strenuous cultivation of plants and animals. In the Mediterranean area early man must have had not only to clear forests before he sowed es planted, but to bring water to his elds.