An analysis of urban heat islands in Tokyo and its environs: the comparison of cloudless nights with cloudy nights in autumn

Abstract

On cloudless nights, the heat island intensity increases from sunset, becomes maximum at midnight, and continues until early morning. On cloudy nights, the heat island intensity increases from sunset, becomes maximum at midnight, and declines towards early morning. On cloudless nights, the cooling rate in rural areas is faster than in urban areas from sunset to midnight. It is at the same level after midnight towards early morning. On cloudy nights, the cooling rate in rural areas is faster than in urban areas from sunset to midnight. After midnight, however, it becomes faster in urban areas than in rural areas towards early morning. -from English summary