How Does Snell's Law Explain Mirages?

Mirages occur due to Snell's Law when light passes through air layers of different temperatures and densities. On hot days, air near the ground is much hotter and less dense than air above it, creating a gradient in refractive index. Light from the sky continuously refracts as it passes through these layers, eventually bending so much that it curves upward. This makes it appear as if there's a reflection of the sky on the ground, which looks like water. Snell's Law governs each small refraction step in this process.