High humidity means high levels of water vapor in the air - the vapor that condenses and becomes visible as "fog" on Windows of air-conditioned cars and buildings on steamy summer days.
The vapour cone effect is caused by pressure differences around the aircraft. A sudden drop in pressure associated with high speed allows water vapour, which is normally invisible, to condense as fog.
蒸汽锥效应是由于战斗机周围的压力差所导致的，高速飞行时压力的陡然降低会使不可见的水蒸气凝结成雾气。
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Upslope fog is usually dense, and extends to high altitudes.