1938: Meteorology

Advances in the science of meteorology continued during 1938 at an accelerated rate, owing not only to increased public interest but to the growth in popularity of aviation and the consequent demand for greater safety in flying. In spite of important improvements in the construction of airplanes and their reduced sensitivity to atmospheric conditions, an accurate knowledge of the behavior of the atmosphere still remains an essential to the success of the aviation industry. As always, the primary objective in advancing the field of meteorology is increased accuracy in weather forecasting.

The United States Weather Bureau has joined with the Massachusetts Institute of Technology to experiment in long-range forecasting. It is their hope to be able to predict the weather for periods of weeks and perhaps even seasons ahead, with relative accuracy. The results of these experiments naturally will not be available to the public for several years. Blue Hill Observatory, Milton, Massachusetts, is closely associated with this program.

Direct Observations.

Both short-range and long-range forecasts depend upon an understanding of the behavior of the upper air as well as that at surface levels. To this end, frequent observations of temperatures, barometric pressure, and humidity over wide areas in the upper levels are essential. The problem of obtaining such data at low cost has approached nearer solution during the past year, as improvements have been made in that remarkable instrument known as the radio-meteorograph. (This term will probably remain in use for a time, although the United States Weather Bureau has adopted the word 'radiosonde' in conformity with French and German usage.) One of the most recent refinements in the instrument has consisted in the replacement of the hair hygrometer by an electrical hygrometer especially adapted for a quick recording of the humidity when the balloon carrying the radio-meteorograph is in very rapid ascent.

The radio-meteorograph is steadily replacing the airplane for use in making upper-air soundings. This instrument sent aloft attached to a small free air balloon may reach heights ordinarily of well over ten miles, sending back the desired data at frequent intervals during its ascent. (In 1938 a record height of 95,000 feet was reached.) Not only are the hazards of airplane ascents avoided, but the cost of obtaining observations in this manner is lowered. The major objection involves the likely loss of the radio-meteorograph itself. This will be less serious as the cost of the instrument is reduced to negligible proportions.

Theoretical Considerations.

Besides advances in methods of making direct observations of the state of the atmosphere, there has been not a little progress in theoretical considerations. The number of men, particularly younger men, devoting attention to the purely mathematical aspects of meteorology continues to grow. Their investigations involve interpretations of the general planetary circulation of air, vertical cross-sections of air masses, and the behavior of the air in cyclones and anti-cyclones which are revealed by the daily weather map. This work includes synoptic analyses with special reference to rain-storms, snowfall, thunderstorms, flooding, and violent tropical cyclones. Supporting studies in micro-meteorology have been continued. Among these is the collection of data in the Muskingum Conservancy district of Ohio as a part of 'Studies in Climatic Factors of Soil Erosion.' These data present a highly detailed series of observations of the rate of horizontal translation of atmospheric conditions at the earth's surface and may constitute the basis for interpreting mathematically or otherwise the behavior of the circulation of the air within cyclones (lows) and anti-cyclones (highs) under specific circumstances.

Climatic Variations.

Investigations are also going forward in the field of climatic variations. Just as the 'man-on-the-street' has observed what to him seem to be changes in climate 'since he was a boy,' so the meteorologist has noted changes in intensity of the seasons, which he seeks to interpret not as true climatic change but as possible cyclical variations. Correlations with sun spots and other manifestations of solar activity are still in progress. Data are being collected relative to the shifting of ocean currents, identification of the phenomenon occurring through the automatic recording of temperatures of sea-water by ships which regularly cross the major currents.

At the International Geographical Congress held in Amsterdam, July 1938, a special report was presented by the Commission of Climatic Variations of the International Geographical Union. The papers prepared for this report fall in such categories as 'Pre-Pleistocene Changes of Climate,' 'Climates of the Recent Prehistoric,' 'Present-Day Variations,' and others. Interesting progress has been made in observing the relation between climate and tree growth. Students of this subject, having already satisfied themselves that three rings serve as indices to climatic variations of the past, are now attempting to derive a formula from these correlations which will enable them to predict probable cyclical changes of the immediate future.

Marine Meteorology.

The field of marine meteorology is being forwarded through the steady increase in observations by ships on the high seas, by various exploratory parties, and by workers in scientific laboratories along the coasts who are interested in the life of the sea or in the behavior of the ocean itself.

Medical Meteorology.

Another division of meteorology which has been advancing slowly might be termed medical meteorology. Only a few persons have turned their attention to this subject. One of the outstanding students of this subject in the United States concludes that two phases of weather are paramount in their effect upon man. One is the mean temperature level in relation to the rate of heat loss from the body, and the other is the effect of atmospheric instability upon physiological adjustments. This vast field is yet to be fully explored.

Other Fields.

Other fields in which the science of meteorology is finding direct application are radio, agriculture, hydrology, and general business. Techniques in forest-fire weather forecasts have improved, also methods for predicting the formation and dissipation of fog and clouds over coastal waters.

Notable Phenomena.

Perhaps two of the most notable meteorological phenomena of the year were the 5-day rainfall in Southern California, February 27 to March 4, and the New England hurricane of September 21. The rainfall in California was the heaviest recorded for such a period since accurate records have been kept. The hurricane is reported to have been the worst in the history of New England, although claims for severity have been challenged by some persons. Even though the damage from both storms mounted high, the resultant losses may not have been in vain; for they have helped to emphasize the desirability of more observation stations and of increased public financial support for the advance of the science of meteorology.