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Results for “mixed phase clouds”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Star and planetary system formation in collapsing, viscous, rotating clouds

The results of a preliminary investigation of several processes that are of interest both for the formation of stars and for the evolution of planetary systems are presented. It is shown that turbulent viscosity is capable of playing an important role in conveying angular momentum over time scales that are short enough to be significant. Meridional circulation can also act in this fashion during some phases of the evolution. This transport may reduce the probability of formation of the rings that have been found by most earlier investigators. Transport and mixing on a faster than cooling time scale should also inhibit usual modes of fragmentation and the present work casts some doubt on the multiple successive fragmentation scenarios that lead from a massive molecular cloud to a collection of roughly solar mass protostars. The conditions that are probable in the disks that would exist at varying phases of collapse are examined and it is concluded that turbulent viscosity would be very important in a pre-solar nebula.

Wiita, P. J.↗
NASA NTRS1978

Photometry and polarimetry of Jupiter at large phase angles. I - Analysis of imaging data of a prominent belt and a zone from Pioneer 10

Photopolarimetric observations of a prominent bright zone and a dark belt of Jupiter in red and blue light are analyzed which were performed by Pioneer 10 at phase angles of 12, 23, 34, 109, 120, 127, and 150 deg. Geometric and photometric reductions of the imaging data are described, the instrument sensitivity at various times is evaluated, and the data are referred to an absolute scale. The observations are analyzed in detail by comparing the data with results of radiative-transfer calculations for specific scattering models of Jupiter's atmosphere. These models include those with a vertical structure consisting of a layer of Rayleigh-scattering gas above a semiinfinite mixture of cloud particles and gas, those having a small quantity of aerosols in the gas above either the diffuse cloud in a reflecting-scattering model or the top cloud of a two-cloud-layer model, those in which a forward-scattering haze is mixed uniformly with gas, and those containing dust layers. It is found that in both the belt and the zone in red as well as blue light, cloud phase functions are required which provide both strong forward scattering and some backscattering.

Tomasko, M. G.↗
NASA NTRS1979

Detection of SO2 in the UV spectrum of Venus

The broad absorption feature below 3300 A in the Venus UV spectrum is identified as primarily due to SO2 absorption based on new higher resolution spectra of the 3000-3400 A region showing broad (10 A), unresolved absorptions in the regions at all SO2 band origins between 3000 and 3300 A. SO2 mixing ratios vary from 5 x 10 to the -7th down to an upper limit of 2 x 10 to the -8th at a phase angle of 138 deg. Previous observational determinations of the SO2 mixing ratio were biased toward large phase angles, and consequently did not detect any SO2 absorption at the 10 to the -8th level. The upper limit derived from the CS2 band head at 3206 A is not greater than 5 x 10 to the -8th. The observed range of SO2 mixing ratios is consistent with model predictions based on the sulfur photochemistry at the cloud tops. Ground-based observations of SO2 mixing ratio will provide constraints on models and check on the Venera and Pioneer Venus measurements of the mixing ratios of SO2 and other sulfur-bearing gases with altitude.

Barker, E. S.↗
NASA NTRS1975

Detection of water vapor on Jupiter

High-altitude (12.4 km) spectroscopic observations of Jupiter at 5 microns from the NASA 91.5 cm airborne infrared telescope have revealed 14 absorptions assigned to the rotation-vibration spectrum of water vapor. Preliminary analysis indicates a mixing ratio about 1 millionth for the vapor phase of water. Estimates of temperature (greater than about 300 K) and pressure (less than 20 atm) suggest observation of water deep in Jupiter's hot spots responsible for its 5 micron flux. Model-atmosphere calculations based on radiative-transfer theory may change these initial estimates and provide a better physical picture of Jupiter's atmosphere below the visible cloud tops.

Larson, H. P.↗
NASA NTRS1976

Large Area Crop Inventory Experiment (LACIE). Phase 1: Evaluation report

It appears that the Large Area Crop Inventory Experiment over the Great Plains, can with a reasonable expectation, be a satisfactory component of a 90/90 production estimator. The area estimator produced more accurate area estimates for the total winter wheat region than for the mixed spring and winter wheat region of the northern Great Plains. The accuracy does appear to degrade somewhat in regions of marginal agriculture where there are small fields and abundant confusion crops. However, it would appear that these regions tend also to be marginal with respect to wheat production and thus increased area estimation errors do not greatly influence the overall production estimation accuracy in the United States. The loss of segments resulting from cloud cover appears to be a random phenomenon that introduces no significant bias into the estimates. This loss does increase the variance of the estimates.

Source record↗
NASA NTRS1978

Mariner 9 television limb observations of dust and ice hazes on Mars

Results are presented for a statistical analysis of over 3000 Mariner 9 television reflectance profiles of the planetary limb of Mars for the period from the decaying phase of a global dust storm (southern summer) to southern winter solstice. It is shown that during the decaying phase of the storm, the dust is maintained aloft to high elevations by vertical mixing primarily in the equatorial zone, apparently by the direct or indirect action of the diurnal tide; the result is that the dust decay is much faster in high-latitude regions than near the equator. Significant dust remains aloft in Martian equatorial regions long after the major dust storms have subsided. At the top of the dusty atmosphere, a region exists where temperatures relax toward values expected for a dust-free CO2 atmosphere; this is therefore a region of convective overturning topped by thin condensation hazes resembling terrestrial noctilucent clouds, thereby showing occasionally gravity wave structures.

Anderson, E.↗
NASA NTRS1981

Absorbers seen near the Venus cloud tops from Pioneer Venus

Pioneer Venus Orbiter measurements of planetary contrast at the Venus cloud tops are discussed. Images of the cloud tops at wavelengths between 1990 and 3400 A were obtained by the Pioneer UV Spectrometer together with broadband imagery and polarimetry at 2700 and 3650 A from the Orbiter Cloud Photopolarimeter at Venus phase angles of 33 to 130 deg. The planet is found to be darkest at the point where the UV Spectrometer line of sight penetrates perpendicular to the cloud tops, indicating that the absorbing material must be deep in the atmosphere. The contrast observed at wavelengths shortward of 3200 A is explained by SO2 absorption in the dark regions, while the persistence of the contrast at longer wavelengths requires the presence of an additional absorber or absorbers closely associated with the SO2, and a haze of submicron particles overlying the cloud tops in the bright regions. The correlations found between contrast and polarization indicate that no single constituent or change in vertical structure can account for the UV contrast. The origin of the markings is instead explained by a model in which absorbers subject to photochemical destruction are mixed upward into the cloud top region.

Esposito, L. W.↗