The Scientific American thus speaks of the uses of climatic data:
“What are climatic statistics good for? To this query one is tempted to retort: What are they not good for? Let us set down a few typical cases in which such data are desired.
“A merchant plans to undertake the sale of rubber coats in foreign markets. Hence he wishes to know all about the distribution of rainfall, both geographically and as to season. Which are the rainy regions of the globe? When do the heaviest occur in each of these regions? Where do the prevailing temperatures indicate the need of heavy coats, and where light?
“An invalid contemplates visiting a certain health resort. What mean temperatures occur there at the season of the proposed visit? What ranges of temperature between day and night? How much does the temperature vary from day to day? How much sunshine may be expected? Is the atmosphere moist or dry? What of the winds? Such are some of the questions he is likely to ask.
“A horticulturist proposes to introduce a foreign plant in this country. Where will he find the most favorable climate for it? In order to settle this question he first tries to secure certain information about the climate of the plant’s original habitat—the march of temperature through the season of growth, average dates of first and last frost, normal fluctuations of rainfall, humidity, sunshine, etc. If the desired information is obtained, the next step is to ascertain where (if anywhere) similar climatic conditions prevail in the United States, and this is generally an easy task.
“An engineer is planning a sewer system. He needs data of excessive rainfall for the locality under consideration, so that he may estimate the maximum amount of storm-water the sewers will ever need to dispose of in a given time. Their capacity should not exceed this amount beyond a reasonable margin of safety: otherwise cost of construction would be unnecessarily great.
“This list of examples might be extended almost indefinitely. It will suffice, however, to show how wide a range of climatic information is required to meet all possible demands. The different branches of industry are concerned with different sets of climatic data. One set helps determine the best location for a railroad: another the kind of goods that will be shipped over it and the way in which they will need to be packed and cared for during shipment. The climatic conditions that must be considered in planning a military campaign are quite unlike those that engage the attention of a hydrological engineer in laying out a system of irrigation. Climatic statistics of interest to aviators are not identical with those that bear upon the problems of ecology or forestry or sanitation. In short, climate means different things to different people.”
Christmas in Many Climes. A general idea of the diversification of climate may be gathered from a description of the weather of some particular day of the year as it exists in many different parts of the world. One is too prone to assume that the weather one has on a given day prevails everywhere. For the moment one does not consider the effect of distance from the equator, proximity to large bodies of water, and elevation above sea level and above the surrounding region. When a holiday or any day of special interest occurs, while the weather cannot make the occasion a success, it can quite effectively destroy all pleasure in the event. When we approach the day of all days in the year when two fifths of the people of the world celebrate the natal day of Christ, interest in the weather increases. The little ones of our clime pray that a mantle of snow may cover the ground, so that dear old Santa Claus may come with his reindeer and sleigh. The boys and girls long for the snow-covered hillsides and the glassy ponds; and even our good old grandmother smiles in anticipation of such a Christmas Day as gladdened her heart when she was a wee tot.
It may be interesting to know under what kind of skies the people of other lands celebrate this international holiday. In the Northern Hemisphere places near the same latitude may have weather conditions greatly at variance the one from the other, because of conditions previously explained. It is our winter now; not because the sun is farthest from us, for in five days the earth will reach the time of perihelion in its course around the sun, and be nearer to the central luminary than at any other time of the year, but because the inclination of the earth’s axis causes us to receive the rays of the sun at a lower angle than during any other season and its intensity is reduced. The conditions are reversed to the people of the Southern Hemisphere; they now receive the most direct rays of the sun and have their summer, which is intensified by the nearness of the earth to the sun.
The event that gave origin to our Christmas holiday occurred nearly two thousand years ago in Bethlehem of Judea; and it may be a new idea to us to try to think of the weather that prevailed at that time and the character of the Christmas Day that land may have this year. We know that it was not cold and cloudy on that eventful night so long ago, for the shepherds were feeding their flocks upon the hillsides and the Wise Men of the East beheld a star and followed it. The star shone brightly from the time they left Herod until they reached the place where the Infant lay. We may therefore judge that this part of their journey was made under a clear sky and that the same conditions prevailed at Bethlehem. Weather observations made at Jerusalem, a few miles from Bethlehem, during modern times, show that during December there are less than fourteen cloudy days on the average. The prevailing winds are from the Mediterranean Sea, only thirty miles to the west of Bethlehem, and therefore rarely does the temperature exceed 65° during the day or fall to freezing at night. While there is evidence that the climate is drier now throughout all of the Holy Land than at the birth of Christ, it is highly probable that when He was born the stars were shining brightly and the hills were green and beautiful and the weather smiling its benediction upon the Son of God.