Practical Exercises in Elementary Meteorology

by Robert DeCourcy Ward

(number of rainy days divided by the total number of days); the number of days with thunderstorms, etc.

It is important that the monthly summaries should be discussed in the class, and that the scholars should give verbal statements as to the numerical results which they have obtained. In this way the work will have a living interest, which the mere compilation of summaries does not possess.

CHAPTER IV.

The first thing for any teacher to do who intends to establish a course in meteorology is to secure a supply of daily weather maps. Arrangements should be made to have them mailed regularly from the nearest map-publishing station of the Bureau. It is important that the Saturday morning map, which is usually not sent to schools, should be included in the set, as the break of two days (Saturday and Sunday) in every week seriously interferes with the value of the work that may be done on consecutive maps. The maps should be securely fastened up in the schoolroom or in the hall. It is advisable to keep at least two maps thus on view all the time, in order that the scholars may be able to study the changes from day to day by comparing the last two or three maps with one another. As soon as they are removed from the wall, the maps should be carefully filed away for future reference. They may be conveniently kept in stiff brown paper folders, each month’s maps being enclosed in a separate folder, with the name of the month and the year written on the outside. It is a good plan to keep with the file of maps any newspaper clippings referring to notable meteorological phenomena associated with the conditions shown on the maps. Thus, newspaper accounts of the damage done by a hurricane along the Atlantic Coast; of the blockades caused by a heavy snowstorm in the Northwest; of tornadoes in the Mississippi Valley; of hot waves and sunstrokes in our larger cities, will serve to enliven the study of the maps, and will also help, in later references to them, to recall interesting points that might otherwise escape the memory. It is true that newspapers are prone to exaggerate, and that they are lamentably inaccurate in their use of meteorological terms; but

nevertheless they may often be profitably used in such general studies as these. Besides the complete weather map, the school will need a supply of blank weather maps, as used by the Weather Bureau. These may usually be secured from the nearest map-publishing station at cost price. In the case of the preparation of illustrations for permanent class use, as suggested later, it is advisable to employ the blank maps used as the base of the Washington daily weather maps, and to be obtained, at cost price, on application to the Chief of the Weather Bureau, Washington, D. C. These are larger in size (16¹⁄₂ by 23³⁄₄ inches) than the station maps, and the paper is of a better quality. Colored illustrations with these Washington blank maps as the base furnish an economical, simple, and effective means of teaching elementary meteorology.

CHAPTER V.

In this chapter a series of six consecutive weather maps is taken as the basis of the work. The study of the weather elements on such a series of maps gives a far clearer understanding of the distribution of these elements and of their relation one with another, than if a far larger number of single maps are studied which do not follow one another in regular sequence. Teachers should add to the map-drawing exercises by giving their classes the data from other sets of maps selected from the school files. Summer maps as well as winter ones should be used, in order that too much emphasis may not be laid on winter conditions. The search for the various cities in which Weather Bureau stations are established, involved in the work of entering the data on the blank maps, furnishes excellent practice in geography. This exercise may be varied, and practice in the location of the different States may be given, if the teacher reads out to the class the temperatures in different parts of the various States, as, e.g., central Arizona, 34°; southwestern Tennessee, 30°; northern Nevada, 38°, etc. As the State names are not given on the Weather Bureau maps, such a method as this will give a very desirable familiarity with the relative positions of the States of the Union. If the school possesses a blackboard outline map of the United States, it may be a good plan, if the class is small, to

have one of the pupils enter the temperatures and draw the isotherms on the board before the class, and to let the others correct him if they see that he is going wrong. As to irregularities in the isotherms, which may cause trouble, the officials of the Weather Bureau vary somewhat among themselves in dealing with such cases, and no definite rules can be laid down to fit all occasions. It is best to select maps with few irregularities at first, and in time experience will show how the exceptional cases may be treated.

By the scheme of coloring isothermal maps, suggested in this chapter, a valuable series of permanent illustrations of noteworthy weather types for class use can readily be prepared at very slight cost. For the purposes of these colored illustrations it is best to use the large scale Washington blank weather maps, as suggested in the preceding chapter, and to have each map mounted on heavy cardboard after it has been colored. By means of this mounting the maps are prevented from tearing, and can be kept smooth and in good condition.

The scheme of coloring may be varied to suit the fancy of the scholars, for the preparation of these permanent illustrations may well be intrusted to those of the class who are especially interested in the work, and who are skillful in their use of the paint brush. The work is really very simple and needs only ordinary care. As soon as the drawing of isotherms and the coloring of isothermal charts have been sufficiently studied, the teacher should hang up the daily weather map each day (or a blank map with the isotherms for the day drawn on it), and should call attention to the temperature changes from day to day. In this way the facts of actual temperature changes experienced by the class will be associated with the larger temperature changes shown on the weather maps.