Optical seeing-mechanism of formation of thin turbulent laminae in the atmosphere.

Data from balloon soundings taken at sites in the Canary Islands, France, and Chile are used to show that hydrodynamic instability, perhaps engendered by the propagation of buoyancy (gravity) or other waves, leads to the formation of thin, turbulent laminae, or "seeing layers." These seeing layers occur almost invariably in pairs and exhibit large values for the temperature-structure coefficient C(T)(2) because they form where the gradient of temperature is particularly steep. The refractive-index-structure coefficient is correspondingly large, and so these layers adversely affect the quality of optical propagation.

Significance of anisotropy and the outer scale of turbulence for optical and radio seeing.

The small value found for the outer scale of turbulence (namely, View Article and Find Full Text PDF

Outer scale of turbulence appropriate to modeling refractive-index structure profiles.

The outer scale of turbulence L (0) has been calculated from values of the refractive-index structure coefficient C(2)(N) obtained from spatio-angular correlation measurements of stellar scintillation. It is found that L(0) View Article and Find Full Text PDF

Cutaneous pneumocystosis.

A 42-year-old man with the acquired immunodeficiency syndrome (AIDS) presented with a 9-month history of progressive hearing loss and bilateral external auditory canal masses. Biopsy of the right ear mass detected Pneumocystis carinii. The patient was treated with a 7-day course of intravenous trimethoprim, followed by a 3-week course of oral trimethoprim-sulfamethoxazole, with a marked reduction in the size of his ear masses.

Optical effects of thermal structure in the lower atmosphere.

Ascending convective plumes of inhomogeneous warm air interspersed with regions of air that are remarkably free from temperature fluctuations are sometimes observed in the lower layers of the atmosphere. A close correlation is demonstrated between intervals of good optical seeing along an upwardslanting path 20 m long and such periods of below average, air-temperature fluctuation. This correlation is sensitive to the azimuthal angle between wind direction and the vertical plane containing the optical path.