Re: mirage off winter snow
Snow and other white objects reflect light and heat. On a sunny day this may happen. Its not your imagination. Use it to your advantage for detecting wind direction and speed for greater shooting ability.
Long range shooting is a process that ends with a result. Once you start to focus on the result (where the shot goes, how big the group is, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.