Man's physical universe

xanabras

UNIT IV

SECTION 7

CLIMATE AND WEATHER ARE PRODUCED BY

PHYSICAL CHANGES

Introduction.

In general man seems to thrive best in climates in which extremes of

heat and cold, dampness and dryness are avoided. A climate can be too

equable; a climate of unvarying temperature, whether it be hot, cold,

or ideal, is not only monotonous but depressing and enervating. Man

seems to do his best work in climates where the temperature changes

decidedly from season to season and from day to night.

It is the object of this Section to show that climate and weather

are a matter of physical cause and effect. This study of climate and the

weather is generally referred to as the science of meteorology.

Climate Is Controlled in Part by the Distribution of Land and Water.

Continental climates show greater temperature ranges, less frequent

rainfall, and more sunshine than marine climates. Desert climates

represent the extreme of continental climatic conditions, with their

hot days, relatively cool nights, and low average rainfall.

Large bodies

of water experience relatively small or slow temperature variations

because of the high specific heat of water, as has previously been

explained. In the daytime a large portion of the sunlight is lost by

reflection from the surfaces of bodies of water, while much of that sunlight

which is absorbed is used up in the process of evaporation. The

amount of sunlight that is absorbed as heat is insufficient to raise

the surface temperature of the ocean even a degree in a day because of

the high specific heat of water and the cooling effect of evaporation.

Land areas, on the other hand, reflecting less heat than water areas

and being composed of materials of relatively low specific heat, become

heated or cooled rapidly. Heat is also distributed by motions within

the water, whereas land is immobile.

The climate on the western shores of continents in the temperate

zones is generally more equable than that on eastern shores due to the

eflfect of the prevailing winds from off the oceans. The prevailing winds

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