大气光学是地球大气层独特的光学性质所造成大范围且壮观的光学现象。美丽的蓝色天空是瑞利散射的直接结果，它重新定向了高频（蓝色光）的阳光，使它们重新回到观测者的视野。由于蓝色光比红色光容易散射，当日出和日落时的阳光必须穿透浓厚的大气层时，太阳看起来就呈现偏红的色调。在天空中额外的颗粒会以不同的角度色散不同的颜色的光，在黎明和黄昏创造出多采多姿的发光天空。冰晶和其它颗粒将在大气层中的光线散射，造成晕、晚霞余晖、华 (光象)、云隙光和幻日。这些种现象的变化是由于粒子大小和不同的几何形状。

海市蜃楼是光线受到大气层的温度变化而产生偏折弯曲的光学现象，会使远方的影像流离失所或是严重的扭曲。与此相关的其它光学现象包括新地岛效应，会使视太阳比预测的提早升起或是延后落下，并且造成形状的扭曲。一种称为复杂蜃景的壮观形式是由温度反演造成的，会将地平在线，甚至地平线下的对象，像是岛屿、崖、船舶或冰山拉长且升高，就像"童话城堡"。

Atmospheric optics deals with how the unique optical properties of the Earth's atmosphere cause a wide range of spectacular optical phenomena. The blue color of the sky is a direct result of Rayleigh scattering which redirects higher frequency (blue) sunlight back into the field of view of the observer. Because blue light is scattered more easily than red light, the sun takes on a reddish hue when it is observed through a thick atmosphere, as during a sunrise or sunset. Additional particulate matter in the sky can scatter different colors at different angles creating colorful glowing skies at dusk and dawn. Scattering off of ice crystals and other particles in the atmosphere are responsible for halos, afterglows, coronas, rays of sunlight, and sun dogs. The variation in these kinds of phenomena is due to different particle sizes and geometries.