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A multiwavelength photometric analysis was performed in order to study the sub‐structure of a sunspot light bridge in the photosphere and the chromosphere. Active region NOAA 8350 was observed on 1998 October 8. The data consist of a 100 min time series of 2D spectral scans of the lines Fe i 5576 Å, Hα 6563 Å, Fe i 6302.5 Å, and continuum images at 5571 Å. We recorded line‐of‐sight magnetograms in 6302.5 Å. The observations were taken at the Dunn Solar Telescope at US National Solar Observatory, Sacramento Peak. We find evidence for plasma ejection from a light bridge followed by Ellerman bombs. Magnetograms of the same region reveal opposite polarity in light bridge with respect to the umbra. These facts support the notion that low‐altitude magnetic reconnection can result in the magnetic cancellation as observed in the photosphere.

An analysis of high-resolution G-band images of active region NOAA 10930 is presented. The observations were recorded with the Broadband Filter Imager (BFI) attached to the Solar Optical Telescope (SOT) on board the Hinode mission. We observed dark lanes in umbral dots up to six folds in larger ones. Formation of umbral dots from dark core penumbral filament shows dark lanes. The evolution of the light bridge from the dark core penumbral filament is observed, which further disintegrates into umbral dots. These observations are compatible with the simulations of three-dimensional radiative magnetoconvection with gray radiative transfer in sunspot umbra by Schüssler & Vögler, which support the notion that these structures appear as a result of magnetoconvection.

An analysis of high-resolution Dopplergrams and continuum images of NOAA AR 8350 is presented. The observations were recorded with the universal birefringent filter attached to the Dunn Solar Telescope at the National Solar Observatory, Sunspot, New Mexico. We find upward velocity of the order of 400 m s within Ϫ1 umbral dots, surrounded by downward velocity of the order of 300 m s. This observation is compatible with Ϫ1 the simulations of three-dimensional radiative magnetoconvection with gray radiative transfer in sunspot umbra by Schüssler & Vögler, which support the idea that umbral dots appear as a result of magnetoconvection.

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