a shining cloud that appears in highlatitudes after sunset or before sunrise, called noctilucent cloud
夜光雲という,高緯度地方で日没後及び日の出前に現われる輝きを帯びた雲 - EDR日英対訳辞書
The observation point attached with the solar battery 7 on a flat column 8 is mounted at the spherical surface of the transparent terrestrial globe 1 and the intensity of the mimic sunshine at each of the respective earth's axis inclination angles is measured by measuring each electromotive force from the low latitudes to the highlatitudes. 透明地球儀(1)球面に、扁平な円柱(8)に太陽電池(7)を付けた観測点を付け、模擬太陽光の強さを地軸傾斜角ごとに低緯度から高緯度の各起電力を測定する。 - 特許庁