noun
westerlies; prevailing westerlies
Meteorological term for the dominant west-to-east winds in the mid-latitudes.
偏西風の影響で、日本では天気が西から東へ変わることが多い。
Due to the westerlies, weather in Japan often changes from west to east.
貿易風 are the easterly trade winds in the tropics, while 偏西風 are the westerlies in the mid-latitudes.
Compound of 偏 (へん, 'biased, leaning') + 西 (せい, 'west') + 風 (ふう, 'wind'), literally 'westward-leaning wind'.