also: ようえん
noun
heat haze; heat shimmer
The shimmering or wavy appearance of air above hot surfaces, such as asphalt in summer.
夏の道路に陽炎が立っていた。
A heat haze was shimmering above the summer road.
陽炎で向こうの景色がゆらゆら揺れて見える。
The distant scenery looks wavy because of the heat shimmer.
Rare on'yomi reading; learners will almost always encounter かげろう.
Kana spelling is common and avoids the unusual reading of the kanji.
蜃気楼 is a mirage (often a distant, reflected image), while 陽炎 is the shimmering effect of hot air close to the ground.
The kanji 陽 (sun, yang) and 炎 (flame) together suggest 'sun flames,' poetically describing the shimmering air. The reading かげろう is a jukujikun, and its exact origin is uncertain.