Military and naval leaders have always emphasized the fact that a thorough study of the military and naval history of the past is essential to correct ideas and to the skillful conduct of war ill the future. Notwithstanding the fact that great changes in naval weapons have been brought about by the scientific advances of the past half century and by the introduction of steam as motive power of ships, the study of the history of galley and sailing-ship warfare is considered very instructive in illustrating the general principles of maritime warfare. Admiral Mahan tells us that while many of the conditions of war vary from age to age with progress of weapons there are certain teachings in the school of history which remain constant and therefore can be elevated to the rank of general principles.
If we scan the pages of naval history we find that fleet commanders have often failed to consider the importance of the weather factor in formulating and executing their plans of battle. And further study reveals clearly that the weather has exerted a profound influence on the outcome of many famous naval engagements which have influenced the history of the world.
To cite a few examples. In the days of galley warfare, at the Battle of Salamis in 480 B.C. we learn that 400 Persian ships were destroyed by a gale shortly before the battle and many more by a thunderstorm after the first day. Thus a friendly gale aided the strategical or tactical genius of the Greek admiral in bringing victory to his side.
In the days of sail we find again that victory has usually gone to the side which had the weather gage. The defeat of the Spanish Armada in 1588 and the Battle of Trafalgar in 1805 are good examples.
Although sailing ships were much more affected by the weather elements than modern men-of-war, we have only to turn to the history of the World War to prove that weather is still a factor of prime importance. In the Battle of Jutland the effectiveness of the opposing fleets was greatly reduced by fog and mist. And likewise the military-naval campaign at the Dardanelles has been recorded as a glaring example of the failure by the Allies to consider even the normal climatological conditions in the area of operations. We find that the lack of water which could have been expected in the dry season was a serious handicap to the fighting forces. But when we read that a severe blizzard caused the death or incapacitation of as many men as the fiercest battles of the campaign, the importance of the weather element in warfare is strikingly illustrated.
And yet, even though our naval leaders have often ignored the importance of weather in the conduct of naval battles, it is a source of considerable satisfaction to note that seafaring men have made some very important contributions to the science of meteorology.
The American Navy can point to the outstanding accomplishments in the field of meteorology and oceanography of Matthew Fontaine Maury, who is justly known as “the Pathfinder of the Seas.” His wind and current charts of the oceans, first published in 1847, were of inestimable benefit to mariners the world over, and resulted in savings to British and American commerce amounting to many millions of dollars annually by shortening the time of ships’ passages over the various trade routes of the oceans. Although Maury is regarded as the father of marine meteorology, it is not generally known that he was among the first to advocate a system of land meteorology in the United States, and in 1856, 14 years prior to the establishment of the United States Weather Bureau, a bill was presented in the Senate to appropriate funds to establish a system of daily observations based on the details of Maury’s plan.
And today, in tribute to his pioneer researches, on the pilot charts of the various oceans, issued by the Hydrographic Office of the Navy Department, appears the notation “founded upon the researches made and the data collected by Lieutenant M. F. Maury, U. S. Navy.”
After Maury’s time, although some officers were actively engaged in this work, the Navy as a whole was not greatly interested in meteorology until this country entered the World War. In 1917, the then Assistant Secretary of the Navy, Franklin D. Roosevelt, urged his friend Professor MacAdie, of Harvard University, to accept a commission in the Navy for the purpose of organizing a naval aerological service. A number of officers were trained in aerology and by 1918 there were about 50 of them together with 200 enlisted men attached to naval air stations and bombing squadrons in England and France.
Since the war, the steadily increasing importance of aviation in the fleet has been largely instrumental in directing interest to the necessity for an efficient aerological service in the Navy. The needs of naval aviation for accurate and detailed forecasts of weather conditions led to the establishment in 1926 of a postgraduate course in aerology for naval officers.
To Captain W. D. Puleston, U. S. Navy, should go the credit for first calling attention of the Navy Department to the importance of having trained aerological officers in the fleet and for later organizing the first postgraduate course in aerology which was instituted at the Postgraduate School in 1926.
Although the advent of aviation has served to emphasize its influence on naval operations, the weather factor has to be considered in many other phases of naval strategy and tactics. Thus visibility often limits the range at which guns open fi# and affects scouting operations and the disposition of the fleet. The upper winds and the density of the air in the higher levels of the atmosphere enter into ballistic computations because of their great effect upon the motion of a projectile in its flight to the target.
Even in time of peace considerable use can be made of weather forecasts in planning the operations of the various forces of the fleet. Thus forecasts of unfavorable weather conditions for conducting certain maneuvers can result in considerable economy by avoiding the useless expenditure of fuel oil alone.
Today, in recognition of the importance which is attached to the use of aerological information in peace-time naval operations, we find that the Navy maintains aerological units at 15 stations ashore and 14 afloat, all under the general supervision of the Bureau of Aeronautics.
Since 1926, 24 officers have received training in meteorology at the Postgraduate School at Annapolis and at the Massachusetts Institute of Technology. In addition, two experienced officers has been sent to Europe for advanced training in the Norwegian methods of air mass and frontal analysis. A school for enlisted men is maintained at the Naval Air Station Lakehurst, N.J., where an elementary course is given for the junior men and as advanced course in air mass analysis methods is offered to the senior enlisted men who have had several years previous experience in naval aerological work.
Research and development in the Navy.—In recent years our small aerological organization in the Navy has devoted considerable effort to aerological research and to the development of instruments best suited to the special requirements of the fleet and of naval air stations.
For several years the Bureau of Aeronautics has been interested in the investigation of the use of static bearings as an aid in detecting weather disturbances. We have conducted independent investigations at naval air stations and have cooperated with the Hydrographic Office in obtaining bearings of atmospherics and correlating them with existing weather conditions as shown on the weather map. Recently the Bureau of Engineering has developed improved equipment for recording bearings of static sources and a new program of research will be undertaken soon under the joint supervision of that bureau and of the Bureau of Aeronautics. Extensive investigations in this field have been carried on in England and their results in a majority of cases seem to indicate a positive correlation between sources of atmospherics and meteorological activity, particularly thunderstorms. The results of our previous work have not been conclusive enough to prove that distant storms, fronts, and other disturbances can always be located by cross bearings of static sources, but it is hoped that the results of the new investigation furnish data on which definite conclusions as to value of this system can be drawn.
Naval aerological personnel were among the first in this country to make upper air flights in planes equipped with recording instruments to obtain data on the vertical structure of the atmosphere, which is of great practical use in modem methods of weather forecasting. The instruments carried on these flights are called aerographs and they record the temperature, pressure, and humidity of the air column. These data permit the preparation of certain thermodynamical diagrams which are of value in predicting thunderstorms, cloudiness, and atmospheric turbulence. Flights of this nature are a regular feature of the daily aerological work at naval air stations and from certain ships of the fleet. The hundreds of flights which have been made in the San Diego area have contributed greatly to a better understanding of the causes of the formation of the low clouds or “high fogs” which are typical of the California coastal regions and which have large influence on aircraft operations in the fleet.
Investigations of the gustiness of winds have been conducted at the Naval Air Station, Lakehurst. This problem is of considerable importance in lighter-than- air operations particularly in the groundhandling of rigid airships of the size of the Macon.
The problem of dissipation of fog has long engaged the close study of the Bureau of Aeronautics, which has conducted experimental investigations of various methods of clearing a landing field of fog.
Aerological and climatological surveys for the fleet and for naval aviation purposes have also been prepared and we have co-operated with the Goodyear- Zeppelin organization in preparing data for their survey of sites for commercial airship bases on the east coast.
In the field of instrument design the Bureau of Aeronautics has been responsible for the development of a number of new aerological instruments and for improvements in design of existing equipment in use in this country.
In 1927 a special shipboard theodolite for making observations of upper winds from a moving ship was developed for the Navy and, by placing trained personnel on a number of ships of the fleet and on a few naval transports, we have contributed to the meager data available on upper winds over the oceans.
In the past two years the aerological section of the Bureau of Aeronautics has concentrated upon the development of several new instruments in an effort to solve the special problems which arise in obtaining shipboard aerological observations and to meet the demands for accurate instruments for naval air stations.
A new anemometer has been developed for use in the past year and has proved to be the most accurate anemometer available in this country today. The development was the result of a long series of tests in the wind tunnel at the Bureau of Standards in which anemometer cups of various forms and sizes were tested. Quite by accident it was discovered that anemometer cups with beaded edges gave a much improved performance in turbulent winds and followed more closely the variations in speed of the true wind. Lighter cups, conical in shape, have been substituted for the heavier hemispherical cups in the present anemometer and all electrical connections have been placed inside the case.
In order to obtain an improved type of gust recorder for airship bases the well- known Dines pressure tube instrument for recording wind direction and velocity has been redesigned. Instead of using the principle of a float moving in a liquid solution to measure the variations in wind speed a diaphragm operating on the bellows principle has been used. Wind tunnel tests and reports from our airship bases have been so encouraging that all previous instruments of this class in use at other naval air stations have been converted into the new type.
A precision aneroid barometer is being developed for use on ships of the fleet. The accurate reading of a mercurial barometer on board a ship which is pitching or rolling excessively is very difficult, even when using a barometer of the constricted tube principle. It is hoped that a precision aneroid which will closely approximate the accuracy of a mercurial will result from this development. This aneroid is based on the same principle as the sensitive altimeter used in naval aircraft.
At the present time preliminary tests are being conducted at the Bureau of Standards on a new type of humidity indicator which is based on the electrical conductivity of the moisture in the atmosphere. The measurement of atmospheric humidity by means of the various types of instruments which are available today is easily the most unsatisfactory of all meteorological measurements, especially at low temperatures. It is well known that the hair hygrometer which is used in recording instruments such as the hydrograph and aerograph is inaccurate, will not repeat itself, and has an excessive lag which probably causes large errors in determining the moisture conditions in the upper atmosphere on airplane flights. If a satisfactory service instrument based on the new principle under investigative can be obtained it will be of great value in aerological research. The advantage of having an accurate hygrograph with very little lag is obvious since it will enable us to utilize the full rate of climb of our planes in making daily aerographic flights which in turn will reduce the cost of these flights and permit them to be started later in the morning and thus closer to the time of the regular surface observations.
The Weston-Selsyn wind direction and velocity indicator system has been developed for use on battleships and cruisers in order to permit accurate determination of the true surface wind which is required in launching and picking up aircraft and for gunnery purposes. The velocity equipment consists of a cup anemometer which is coupled to the shaft on an electric tachometer. The voltage generated by the tachometer varies with the speed of the rotating cups and hence with the wind. The indicator is a voltmeter graduated in knots. For wind direction a standard wind vane which drives a self-synchronous motor is used, the direction being indicated on a dial graduated in degrees. Of course this instrument indicates apparent wind but the true wind can be determined in a few seconds by means of the plotting board used in plotting soundings of the upper winds.
Final calibration and flight tests have been completed on a new aerograph which represents a definite improvement in accuracy and sensitivity over the present instrument used by the Navy and Weather Bureau. In this instrument we have incorporated the best features of certain foreign aerographs. The chief feature of the design is the placing of the temperature and humidity elements in a ventilation tube which is exposed to an air stream of about 50 miles per hour while the plane is in flight. The rapid movement of air past these elements reduces their lag so that more accurate registration of temperature and humidity conditions in the upper air is possible. Tests at the Bureau of Standards showed that the time lag of the temperature element in the new instrument with a ventilation speed of 50 miles per hour is 7.5 seconds, compared to a lag of 60 seconds in the present aerograph. It is expected that this improvement in lag characteristics will permit a more rapid rate of ascent of airplanes making aerological flights, which at present are restricted to a rate of climb of 300 feet per minute.
Preliminary investigations of a radio meteorograph for naval use are being conducted. The device consists of the usual pressure, temperature, and humidity elements and a small radio transmitter which sends out a characteristic signal whenever the temperature, pressure, or humidity of the air changes a definite amount, a radio receiver being used to pick up the signals from the transmitter.
The instrument is attached to a sounding balloon which usually ascends well up into the stratosphere before bursting. The advantages of such a device are: (1) it can be sent up in bad weather, such as dense fog, when planes are unable to take off; (2) data from higher altitudes are obtained; (3) the temperature, pressure, and humidity data are plotted immediately as the signals are received.
Of course the instruments are seldom returned so that they cannot be used in place of making daily airplane ascents unless the price in quantity production is brought down to equal the cost of making the flights by plane.
Other instrument developments include a microbarograph for recording small changes in atmospheric pressure on an open scale and special calibration equipment for testing various recording instruments. The Bureau of Aeronautics has received valuable assistance from the aeronautical instrument and wind tunnel divisions of the National Bureau of Standards in the design, testing, and calibration of aerological instruments.
In the past year there have been several significant developments in the field of meteorology in this country and abroad which give promise of increasing the accuracy of all types of weather forecasts.
The first was the appointment by the President of a committee of the Science Advisory Board to investigate the service rendered by the Weather Bureau.
The major recommendations of this committee were: (1) that the so-called air-mass analysis methods of weather forecasting be adopted in the Weather Bureau; (2) that the number of daily weather maps in the United States be increased to four; and (3) that the number of stations making daily aerological flights by airplane be increased to 25, utilizing wherever possible the services of Army and Navy planes.
It was a source of much satisfaction to the Bureau of Aeronautics to note that the recommendations of this committee, which included many outstanding scientists, were in close agreement with those suggestions for improvements in the weather service in the United States submitted after the destruction of the Akron by the chief of the Bureau of Aeronautics, Rear Admiral E. J. Kang.
In the past year much has appeared in this country about these air-mass methods of weather map analysis and forecasting, or frontal methods as they are generally known among meteorologists. The general tenor of these newspaper stories is that these methods are new developments which have originated in this country and have only recently been placed in use. In reality these methods are not new, even in the United States, for they are based on the polar front theory of atmospheric circulation which was first put forward in 1922 by J. Bjerknes and H. Solberg, celebrated Norwegian meteorologists. The application of these methods to American weather problems dates back at least to 1926. Naval aerologists, trained in the use of these methods at the Massachusetts Institute of Technology, may be classed among the first to make use of the Norwegian system of forecasting in its application to naval weather problems and they have long advocated their widespread adoption in this country.
Our application of these Norwegian methods has been restricted because of the lack of adequate data in American weather reports and the infrequent weather map observations. When the recommendations of the Science Advisory Board are placed in effect the additional data and more frequent weather observations thus available should be reflected in considerable improvement in all types of weather forecasts in this country.
The use of these methods in the Navy has been given increased impetus in the past few years as a result of the reports submitted by officers who have studied under Dr. Bjerknes and his colleagues at the Geophysical Institute, Bergen, Norway. A detailed report on the Norwegian system, prepared by Lieutenant Commander Reichelderfer in 1931, has received a wide distribution in the U. S. Weather Bureau service and has been made available as well to several units of the Army and to commercial air lines.
In 1933 an advanced course for senior enlisted aerographers was organized at the Aerographer School at Lakehurst for the purpose of instructing them in these modem methods of forecasting. Many of the aerographers trained by the Navy have found employment with the commercial air lines upon separation from the service.
The Navy is playing an important part in the enlarged airplane observational program which was inaugurated on July 1 of this year. Regular daily flights are being made from the naval air stations at Anacostia, Lakehurst, Norfolk, Pensacola, San Diego, Sunnyvale, Seattle, and Pearl Harbor. A few other stations, such as Philadelphia, Dahlgren, and Coco Solo, make occasional flights for local forecasting purposes, the data obtained being likewise transmitted to the Weather Bureau. In addition the following ships of the fleet make flights of this nature both in port and at sea: Saratoga, Lexington, Ranger, Wright, California, and Chicago. Valuable data on the vertical structure of the air over the ocean and near the coast have been obtained as a result.
At the shore stations making regular flights the take-off is usually about 0500 so that the data are available in time for use in preparing the morning weather forecasts. The average altitude obtained on these flights is over 17,000 feet, the airplane climbing at the rate of about 30 feet per minute, leveling off at intervals of 3,000 feet in order to reduce the effect of lag in the temperature and humidity elements of the aerograph.
In June of this year a conference was held at the California Institute of Technology for the purpose of discussing the meteorological problems of the Pacific coast with particular reference to the steps necessary to be taken to utilize completely the methods of air mass analysis in that area.
Naval aerologists have had considerable opportunity to become acquainted with the peculiarities of Pacific weather in their daily forecasting work for operations of the fleet. The aerological officers who represented the Navy at this conference made the following recommendations for improved weather reporting service in the Pacific area which were considered as necessary or desirable steps in the program of the Science Advisory Board for the adoption of the air mass analysis methods:
- More weather reports should be obtained merchant ships, including four observations and more complete data in reports. Merchant ships should be equipped with better meteorological instruments and a system of training their observers in the making of complete meteorological observations should be inaugurated.
- Certain selected ships on regular routes should be furnished with equipment for making observations of upper winds and of cloud heights.
- A few completely equipped mountain observatories should be established in the Pacific coastal states.
- More meteorological stations should be established along the coast and on islands near the coast, and particularly San Nicolas, Santa Barbara, and Catalina Islands.
- The weather broadcasts from Siberian stations should be intercepted and re-broadcast as a probable aid in extending the time range of Pacific weather forecasts.
- The International Weather Code or a suitable modification of it should be adopted in this country.
The following program of research into the causes of certain characteristic weather phenomena of the Pacific coast was also suggested:
- An Investigation of the low clouds and fog of the California coastal region and of the upper air temperature inversions associated with them.
- An investigation of the Santa Ana wind storms, particularly of the vertical structure of the air in the lower levels during this condition.
- A more complete investigation of the characteristic properties of the air masses typical of the Pacific coast utilizing data from routine airplane soundings and from the proposed mountain observatories.
Recent developments.—Although the Norwegian methods of weather chart analysis have been developed to a high degree of perfection, the step from the completed physical analysis to the forecast is still a rather difficult one. However, in the past year, Pettersen in Norway has developed a system of predicting by mathematical equations the instantaneous velocity and acceleration of various pressure formations such as cyclones, anticyclones, troughs, wedges, and fronts, their displacement and variation in intensity during the forecasting period, and the deepening and filling up of pressure systems. The results obtained to date have been so promising that there is but little doubt that these methods will largely increase the accuracy of weather forecasting.
There is no question but that these methods will prove to be a great aid in increasing the accuracy of weather forecasts in the United States, especially for the central and eastern parts of the country because of the frequent observations which can be obtained from stations to the westward. These forecasting equations are expressed in terms of atmospheric pressure only and on short period changes in pressure, and thus emphasize the importance of accurate reports of pressure and pressure changes. Pettersen believes that greater accuracy in weather predictions by these methods, even for periods in excess of 24 hours, would be obtained if the amount and character of barometric changes were observed more accurately and if the time interval between weather charts were shorter.
An analysis by Dr. Pettersen of the weather maps for the day of the Akron disaster showed that by means of these formulas he was able to predict the development and rapid rate of movement of the secondary cyclone, or “wave disturbance” as it is technically called, in which the Akron found herself on the night of April 3, 1933.
In the past few months the applications of these equations in our forecasting work at the Postgraduate School and in Washington have given promising results.
The importance of ocean meteorological information is gradually coming into fuller realization now that plans are actively under way for transoceanic flying service. An efficient meteorological service will be one of the most important requisites for a safe and dependable commercial aviation service across the Atlantic and Pacific Oceans. The press has lately revealed the plans of leading American and foreign aviation organizations for early establishment of transoceanic routes. It is certain that these companies are making a thorough study of the meteorological problems involved. All of which emphasizes the importance of the program of furnishing better instrumental equipment and for training observers on ships of the merchant marine submitted by naval aerologists at the Pacific Meteorological Conference last June.
With observers on merchant ships trained in making aviation weather reports, the planes or airships flying over ocean routes could receive frequent reports of surface and upper air conditions from ships along the course, thus adding to the safety of flying.
It is believed that the Navy aerological organization is making a valuable contribution toward furthering our knowledge of the weather of the oceans both at the surface and in the upper air and that we will continue to play an important part in the collection of ocean meteorological information.
The aerological organization of the Navy relies upon the U. S. Weather Bureau for nearly all of the meteorological information upon which it bases its weather forecasts for naval activities and in return for this valuable service has always co-operated to the fullest extent in furnishing meteorological information from naval air stations and from ships at sea. This co-operation consists in transmitting to the Weather Bureau central offices reports of airplane observational flights, pilot balloon soundings, and surface weather observations. Copies of certain aerological summaries are forwarded monthly to the Weather Bureau and all naval aerological records are made avail' able to them for special study.
The Navy Department, by means of its naval communications system, plays a large part in disseminating a vast number of meteorological reports, forecasts, and storm warnings for the Weather Bureau for the benefit of aviation, commerce, and navigation. At the present time broadcasts of this character are transmitted regularly from 26 naval radio stations.
In order that the Weather Bureau may have information of weather conditions in the far corners of the earth, the Navy intercepts weather broadcasts from Siberia and retransmits them to San Francisco and Washington, while the flagship of our Asiatic Fleet sends a special message daily containing reports from China, Japan, and the Philippines. For the benefit of European meteorologists a special bulletin is transmitted from Washington daily containing reports from the United States and Canada.
In addition to its manifold activities outlined in this article, the naval aero logical organization is attempting to keep abreast of the latest developments in the science of meteorology both in this country and abroad with the thought in mind that accurate and detailed weather forecasts are going to play an increasingly important role in naval operations both in peace and in war.