Vertical Field Structure Research Articles

Plasma Flows Observed in Magnetic Flux Concentrations and Sunspot Fine Structure Using Adaptive Optics

We present diffraction-limited observations of magnetic flux concentrations and penumbral and umbral fine structure within an active region observed at disk center. We recorded G-band images, magnetograms, Dopplergrams, and narrowband filtergrams, using the Universal Birefringent Filter (UBF) at the Dunn Solar Telescope (DST). The National Solar Observatory (NSO) adaptive optics system at the DST was used to achieve diffraction-limited long-exposure imaging with a high signal-to-noise ratio. The main results can be summarized as follows: Strong and spatially narrow downflows are observed at the edge of magnetic structures, such as small flux concentrations (sometimes also referred to as flux tubes), pores, a light bridge, and the sunspot umbrae. For the particular sunspot observed, we find strong evidence for what appear to be vigorous, small-scale convection patterns in a light bridge. We observe extremely narrow (<02) channels or sheets of downflowing plasma. Flux concentrations as seen in intensity expand from a height close to where the continuum is formed to the height of formation for the G band. These observations indicate that the G band forms in the mid-photosphere. We are able to identify individual penumbral fibrils in our data and find a bright (hot) upflow and a more vertical field structure at the filament footpoint near the umbral boundary. The observations are consistent with a filament geometry in which the field and flow turn to a nearly horizontal, dark structure over a distance of about 02. In the deep photosphere we observe strong upflows of the order of 1 km s-1 in umbral dots. We compare our results with theoretical model predictions.

Formation of Brillouin waves in the underwater sound channel

The mechanism of the vertical sound field structure formation in the underwater sound channel is considered. The calculations are performed by the ray method for the rays that have upper turning points at the ocean surface. It is shown that the vertical field structure is formed by the ray pairs producing opposing waves in the vertical. The rays belonging to one pair have the same sign of their departure angles at the source. The pairs are formed because of the presence of a minimum in the ray cycle length as a function of the departure angle. The resulting ray pairs are analogs of Brillouin waves.

PRESENT STATE OF RESEARCH ON ATMOSPHERIC ELECTRICITY

Introduction 292 1. Basic Information 294 2. Two Theories 297 3. Vertical Structure of Field, Conductivity, and Current in 299 4. Distribution of Space Charge in the Atmosphere 302 5. Time Variation of Field and Potential at High Altitudes 303 6. Description of Electric Processes in Regions of Good Weather 305 7. Electricity of Stratified Clouds 307 8. Electricity of Cumulus and Cumulus Congestus Clouds 311 9. Structure of Shower and Thunderstorm Clouds 313 10. Accumulation of Charges in Thunderstorm Clouds 316 References 320