One of the biologically most important parameters of the cloudy sky is the proportion P of the celestial polarization pattern available for use in animal navigation. We evaluated this parameter by measuring the polarization patterns of clear and cloudy skies using 180 degrees (full-sky) imaging polarimetry in the red (650 nm), green (550 nm) and blue (450 nm) ranges of the spectrum under clear and partly cloudy conditions. The resulting data were compared with the corresponding celestial polarization patterns calculated using the single-scattering Rayleigh model.
(參考資料來源於谷歌）
Sky Angle（天體生物學術語）可翻譯為穹體雨雲角：生物學意義上有雲天空所具有的最重要特質之壹，是壹種動物通過磁感應識別方位的媒介。可以通過地磁180度的維度去測量穹體雨雲角的角度。得到的結果可以與地磁場進行進壹步的比較來估計其程度。
簡而言之，穹體雨雲角為壹種動物使用的壹種生物導航系統。
Ps.天空中雨雲隱約形成的較長的銳角即為Sky Angle
附圖片兩張（圖片來源於谷歌圖片搜索）：