Descriptive Meteorology

Definition of Climate. --From the Greek word κλίμα, slope or inclination. The term was used to denote the effect of the oblique rays of the sun on the temperature of the earth and its atmosphere. To-day it is applied to the summation of the atmospheric conditions as recorded for a long period of time; or, in other words, it is the totality of weather, while "weather" is the physical condition of the atmosphere at a given time, or during a limited period.

One may well speak of the weather of to-day, or of last month, or of some past year, but not of the climate of a day, a month, or a year. The climate of a place is ascertained by a study of its continuous weather records for a long period of years--the atmospheric pressure, the temperature, the rainfall and snowfall, the time and frequency of frost, the extremes of heat and cold, the direction and velocity of the wind, the amount of air that flows from different points of the compass, the amount and the intensity of sunshine, the humidity and transparency of the atmosphere, and its electrification. Climatology is to be considered as a subdivision of meteorology.

Hann, at the beginning of his "Handbook of Climatology,"¹ gives the following definition of climate:

"By climate we mean the sum total of the meteorological phenomena that characterize the average condition of the atmosphere at any one place on the earth's surface. That which we call weather is only one phase in the succession of phenomena whose complete cycle, recurring with greater or less uniformity every year, constitutes the climate of any locality."

The same writer presents an alternative definition, according to which climate is regarded as "the sum total of the meteorological conditions in

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