Captive Balloon Research Articles

Some factors influencing 3 cm radio-wave propagation oversea within and beyond the radio horizon

The results of a number of short-term oversea measurements of the variation of received signal level with range from a 10Gc/s transmitter are presented. It is shown that the variation of signal level within the horizon was rarely that expected for propagation through an atmosphere having a uniform refractive-index gradient. Signal losses of from 5 to 30dB frequently occurred well within the horizon, these losses being recovered when the range between transmitter and receiver was sufficiently reduced. A well-defined interference pattern usually occurred in the region of reduced signal level. Some data on the variation of refractive index with height up to about 700ft above sea-level were gathered using a radio sonde and a captive balloon, but the detail was not sufficiently fine to enable a direct relationship to be established between signal losses within the horizon and the occurrence of irregularities in the refractive-index profile at low elevations.A direct relationship was found to exist between the signal level within the horizon and that propagated well beyond the horizon into the extra-diffraction region.

Power spectra of temperature, humidity and refractive index from aircraft and tethered balloon measurements

Fifty-seven spectra of temperature, vapor pressure and refractive index were computed from captive balloon data taken at elevations up to 3000 feet MSL. Eight spectra of refractive index were obtained using an aircraft equipped with a microwave refractometer. It was found that atmospheric stability apparently has a pronounced effect on the variation of turbulent intensity with height. Although the spectra of all three parameters generally approach a -5/3 power law at high wave numbers, stability seems to have a controlling influence on spectral form at the low-frequency end of the wave number range studied. It is therefore concluded that methods of computing microwave scattered fields from the mean square dielectric perturbations and scale size obtained from the auto covariance are unreliable. The forms of the experimental auto covariances appear to be best represented by an exponential function or perhaps by a Modified Bessel Function of the second kind and 1/3 order. The temperature-humidity cospectrum may influence the shape of the refractive index spectrum, especially under unstable conditions. The equivalence of Eulerian space and time spectra is verified for refractive index by a series of aircraft-balloon fly-bys.

Safety Deflation Device for Large Captive Balloons

A mechanism for the automatic deflation of captive balloons in the event of mooring cable breakage has reduced a hazard to air navigation. Devised at the U. S. Army Electronic Proving Ground (USAEPG) at Fort Huachuca, Arizona, this mechanism has also effected savings in recovered balloons and meteorological instruments.

The measurement of gustiness in the first few thousand feet of the atmosphere

A description is given of instruments which have been designed and used to measure gustiness, in the form of inclination and total speed of the wind, from a position on the cable of a captive balloon. A lightweight wind vane with automatic compensation for tethering cable angle, and a sensitive vane airmeter are used as sensing heads. The data, with reference signals, are relayed by electric cable to ground level and recorded on multi-channel recorders. Both instruments have good response to wind fluctuations with periods down to one second. A brief account is given of some observations made at Cardington, Beds., and some examples are presented of records made at 1,000, 2,000 and 3,000 ft in contrasting meteorological conditions.

The measurement of gustiness in the first few thousand feet of the atmosphere

AbstractA description is given of instruments which have been designed and used to measure gustiness, in the form of inclination and total speed of the wind, from a position on the cable of a captive balloon. A lightweight wind vane with automatic compensation for tethering cable angle, and a sensitive vane airmeter are used as sensing heads. The data, with reference signals, are relayed by electric cable to ground level and recorded on multi‐channel recorders. Both instruments have good response to wind fluctuations with periods down to one second.A brief account is given of some observations made at Cardington, Beds., and some examples are presented of records made at 1,000, 2,000 and 3,000 ft in contrasting meteorological conditions.

Point discharge currents from a captive balloon

Measurements are described of the point discharge current, I, from a point attached to a captive balloon, and these have been correlated with the height, h, the potential gradient at the ground, F, and the wind-speed, W. An approximate theoretical formula is developed, giving I = K( Fh) q−1 W s− q . The observational results check the validity of certain aspects of this formula within a limited range of the parameters, with q about 2.77 and K about 0.02 (or 0.015 after estimating a correction for systematic error in F) when I is measured in μA, Fh in kV, and W in km/hr. Measurements for an eight-point discharger show that this gives in all about half the current from a single point under similar conditions.

けい留気球による空中電気測定

Measurements of the electrical current in the mooring wire of the captive balloon and of the electrical conductivity in the lower atmosphere were carried out from January to October, 1953 at Honjo, Saitama-Prefecture. We observed these two elements in the fair weather nights.The meteorological phenomena in calm days have been considered to have smaller influence on the atmospheric electricity. But from our results, it is considered that the potential gradients at the ground surface are remarkably affected by the meteorological phenomena-nocturnal inversions-in calm nights.

A Century of Air-photography

When I wrote a short history of archaeological and other air-photography in 1928 the earliest examples quoted were those taken by Major Elsdale between 1880 and 1887 ; this information was given me by the late Colonel Sir Charles Arden-Close, himself a pioneer of the craft. Since then two earlier instances have come to light. The Science Museum, South Kensington, has exhibited an air-photograph of Boston, Mass., taken in 1877 ; but unfortunately it has no history. In a book published in 1930 there is reproduced a photograph taken above Paris from a captive balloon, taken by that photographic genius who called himself Nadar. Through the good offices of Professor Vaufrey, editor of L’AnthropoZogie, prints were obtained from the Service Photographique des Monuments Historiques, and two combined are here reproduced on PLATE III. They look towards the Arc de Triomphe, and have on the left the Avenue du Bois de Bouiogne (Avenue Foch) and on the right that of Victor Hugo : note that these splendid thoroughfares, then only a decade old, were still only half built-up (the left hand part of the photograph is defective). Photography itself was not much older, Fox Talbot’s first efforts having been made from 1842 onwards.

A TECHNIQUE FOR THE DETERMINATION OF WATER IN AIR AT TEMPERATURES BELOW FREEZING

Abstract An investigation of ice fog in Alaska required a technique for the determination of the water content of the atmosphere at temperatures between −20 to −55C. No satisfactory method for direct field measurements at these low temperatures was available. A field sampling-technique was developed which consisted of extracting the contained water by bubbling the air through absolute methanol, an aliquot of which was then titrated with Karl Fischer reagent. A visual end-point was applicable. The method permitted rapid titration, required simple apparatus, and measured the amount of moisture in the air directly to within 2 per cent of the absolute values. A method of filtering the air in order to separate water vapor from precipitated water was also developed for sub-freezing temperatures. Humidity observations were extended to levels above the surface by drawing a known volume of air into the bubbler through polyethylene tubing supported by captive balloons. Results obtained with these techniques are inc...

A simple method for shallow meteorological soundings

A method for use with captive balloons is described, by means of which the signals from a modified chronometric radiosonde can be transmitted through a nonconducting mooring string. The devices for transmitting and receiving the signals of the meteorosonde are outlined.

On the Application of Captive Balloons to Carry Photographic Emulsions

On the Application of Captive Balloons to Carry Photographic Emulsions

Captive-Balloon Equipment for Low-Level Meteorological Soundings*

Meteorological equipment for taking detailed temperature and humidity soundings to 3000 ft. altitude is discussed. It consists of a captive balloon wired-sonde system using a ceramic temperature element and an electrolytic hygrometer strip. Similar equipment is also adapted for use in airplane soundings. Calibration techniques and results are discussed, together with a method for correcting the humidity strip to ± 1% R.H. Temperature accuracy is ± 0.1°C. The limitations of the balloon and airplane equipment are discussed and the two are found to be complementary.

氣球面附近の電位傾度

The atmospheric potential gradient near the surface of the captive balloon was measured at various heights from the earth's surface in different meteorological conditions. The bamboo-rod was erected on the surface of the balloon and Polonium-collector was attached to this rod. The lead wire connected the collector and the self-recording electrometer was fastened to the moorings. The potential gradient near the surface of the balloon is so much greater as the height of the balloon increases. When the balloon penetrates the haze-layer, the potential increases with height and reaches the maximum value and then decreases to the normal value with height.

The measured performance of horizontal dipole transmitting arrays

Measurements of the performance of horizontal dipole arrays are described, and are compared with the theoretical performance under ideal conditions. The measurements include polar diagrams, the effect of ground slope and radiation through other arrays, and the performance over a frequency band of ±2% relative to the design frequency, which is typical of the width of existing short-wave broadcasting bands.One method of measurement consisted in elevating a calibrated frame receiving aerial using a captive balloon; by varying the height and position of the balloon, the field strengths in different directions from the array were measured. In the second method a frame aerial at ground level was used; this gave only relative values of field strength and was used mainly to determine the frequency characteristic.It was found that for an array radiating over a flat site free from obstacles there was good agreement between the theoretical and measured performance; the maximum field strength was of the order of 0.8–0.9 of the theoretical value. A sloping site or radiation through other near-by arrays, however, may cause appreciable departures from the theoretical characteristics.An array having no reflector curtain covers the frequency band of ±2% without appreciable loss in radiation efficiency. This is also true for an array with a parasitic reflector curtain which is tuned to the working frequency. If, however, the reflector is tuned always to the mid-band frequency, the radiation efficiency at other frequencies is reduced. The band-width can be increased by reducing the characteristic impedance of the dipoles, and measurements have been made on two types, one consisting of single wires and the other of two parallel wires spaced 6 in apart. For an array of four rows of single-wire dipoles, the band-width is ±1% for a 10% drop in field strength relative to the mid-band frequency; for a similar array of two-wire dipoles the corresponding band-width is ±2%. The band-width of arrays containing less than four rows is approximately the same.

Notes on Small Captive Balloons for Low Altitudes

Notes on Small Captive Balloons for Low Altitudes

Meteorological Effects during the Total Solar Eclipse

DR. C. F. BROOKS, of the U.S. Weather Bureau, has given a brief preliminary account (Bull. Am. Meteorological Soc., Aug.–Sept. 1932, vol. 13, pp. 159–160) of the co-operative effort made in the United States and eastern Canada to determine the effects upon the atmosphere of the total eclipse of the sun on August 31 last. The programme of meteorological observations was determined largely by the Blue Hill Observatory of Harvard University, but the scheme was carried out with the aid of many public bodies and private individuals. Special measurements were made of the radiation from sun and sky; conditions in the upper atmosphere were measured by meteorographs carried by aeroplanes and captive balloons; numerous ordinary meteorological observations were carried out by the regular observers of the U.S. Weather Bureau and by a large number of auxiliary voluntary observers.

Diurnal Variation of Temperature in the Free Atmosphere

THE following results, which I have recently obtained by a discussion of temperatures obtained in kite and captive balloon ascents, may be of interest in connection with Prof. Clayton's letter (NATURE, February 4) and Mr. Dines's remark that at a height of 1 km. the daily temperature variation becomes insignificant (NATURE, June 17). The daily variation of temperature at a height of 1 km. over Berlin, deduced from 2232 observations made during the five years 1903–7, is given in degrees C. by T = T3 - (4.4.40 ± 0.08) + (0.87 ± 0.13) sin (nt+θ2) + (0.14 ± 0.10) sin (2nt+θ2), where T3 is the mean surface temperature, and the probable errors are deduced by the method of least squares. The most probable values for θ1, θ2, are 197° and 123° respectively, the time being measured from midnight.

Man-Lifting Kites

By the courtesy of Mr. S. F. Cody, we are enabled to reproduce some illustrations of his man-lifting kites which have not only aroused public attention, but that of the Admiralty and War Office. Mr. Cody may certainly be congratulated on the success that has so far attended his experiments in man-lifting with his winged-box kites. The trials with his system, both on the ironclads placed at his disposal by the Admiralty and at Aldershot, seem to promise that at no very distant future the captive observation balloon, limited in its use to fairly calm weather, will be efficiently supplemented on windy days by the observation kite. In a well-illustrated pamphlet on the subject which Mr. Cody has recently circulated, he thus describes his method of man-lifting.

Captive Balloon Photography

No one can reasonably deny that panoramic views taken from a moderate height give the best idea of the general features of a town or other locality. When we visit a new district we naturally mount a prominent hill or other point of vantage, and so obtain an impression of the surroundings; and the photographer takes his camera as high as he can to enable the lens to receive the view. Far more extended views are enjoyed by those who indulge in balloon ascents, and photographs taken from the cars of balloons are occasionally secured, and give those who stay at home some idea of the ground as seen by the aëronaut.

Scientific Serials

Meteorologische Zeitschrift, February.—Results of the international balloon ascent, by Dr. H. Hergesell. This is the first of a proposed series of papers; the present one deals principally with the range of temperature, as shown by observations made in a captive balloon at Strassburg on June 7 and 8, 1898. The results prove that in strata of free air, whose height exceeds a few hundred metres, the temperature possesses an extremely small diurnal range. During the night it scarcely amounts to a few tenths of a degree; while in the daytime a variation of some three or four degrees Centigrade may occur, even at a height of 800 metres, when vertical air currents exist. In the absence of these, the range would, in all probability, sink to a very low value.—On the characteristics of mild winters, by Dr. G. Hellmann. The last two mild winters have induced the author to revise his previous researches upon this subject, and he gives particulars of the 51 mild winters experienced in Berlin during the last 180 years. The principal results arrived at are: that mild winters scarcely ever occur singly, but in groups of two or three; that they are usually of long duration, from November to February or March; severe and long, late winters (February and March) seldom occur after mild mid-winters; in mild mid-winters the greatest variations of temperature usually occur in January. After a very mild winter, a warm summer is more probable than after a winter which is only moderately mild. Dr. Hellmann pleads for synoptic charts for the whole globe—at least for short intervals, if longer periods cannot be undertaken.