The K giant Arcturus (alpha Boo) was observed with the Birmingham double magneto-optical filter spectrometer using the GHRIL facility at the Nasmyth focus of the 4.2 m William Herschel Telescope of the Observatorio del Roque de los Muchachos in 1988 April to May. Approximately 80 hr of data were obtained over a 2 week interval. Analysis of the data

The ratios between the amplitudes of p-modes measured simultaneously in the Na and K resonance lines are compared with the expected ratios for adiabatic waves at two different levels in the atmosphere. The results agree within errors with the energy decaying solution for the waves at the photosphere.

Data obtained at the Observatorio del Teide (Tenerife) during the years 1978 to 1988 using a resonant scattering spectrophotometer, is analyzed to look for variations of the low degree p-mode frequencies along the solar cycle. The analysis based on the cross-correlation of power spectra suggests that the variation of its maximum correlation

Effects of differential extinction across the Earth's atmosphere on astronomical photometry are reviewed. Under the same circumstances when a rotating extended object is observed spectrometrically, a residual radial velocity is obtained which varies during the day. In the case of integral sunlight observations, this effect was calculated along the

The question of whether or not solar g-modes can be detected and identified from ground observations is addressed. The limitation imposed by the Earth's atmosphere, the background solar noise spectrum at low frequencies, and a poor theoretical knowledge of these modes are mentioned. Using the best uninterrupted full disk velocity measurements

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