The amount of water vapor in the air. Under trade wind conditions in Hawaiʻi, lower elevations are humid while higher elevations are dry. Above this divide, which fluctuates betweeen 5000-7000 ft (1500-2100 m), relative humidity is generally below 40% and often falls to 5-10%, producing areas with low cloudiness and good clarity. In the lowlands and along the lower mountains, relative humidity commonly averages 70-80% in windward areas and 60-70% in leeward ones. Winter relative humidities are somewhat higher than summer ones.