OCR Text |
Show EQUATORIAL TEMPERATURE - Why is the equator not warmer in January when the earth is nearest the sun that in July? Mr. Croll assigns as the reason that the northern hemisphere, which he calls the cominant hemisphere, having its winter in January, the whole earth is colder at that time, also that the northern trade winds pass further south in January and cool the equatorial regions more that at other seasons. His views are disputed by A. Woiekoff, who denies that the winds and condition of the northern hemisphere have any perceptible influence at the equator and ascribes the mildness and uniformity of the equatorial temperature to the prevalence of the rainy season in our winter, the southern summer months. Water acts during this season to reduce the temperature through its great capacity for heat through the screens of clouds which it interposes between the sun and the surface of the earth, and through evaporation, and this upon the higher as well as upon the lower of air. It is admitted that winds have some effect as aids to the cooling, but the insignificance of their influence, as against any active heat-producing force, and in the absence of moisture, is shown by the fact that the Sahara, is the hottest region in the world, notwithstanding the winds blow over it from the cool Mediterranean. |