To reduce any atmospheric distortions, astronomers try to view objects that are as close to straight up as possible. Since the atmosphere is at its thinnest straight up, the atmosphere will have the least impact on any object viewed. Only with the Hubble Space Telescope, have astronomers finally been able to eliminate the atmosphere from their viewing. Of course the weather plays a major part in astronomy. If the sky is full of clouds, it is very difficult if not imposable to view anything.
Humidity reduces how much light passes through the atmosphere.
Professional astronomers tend to build their very large and expensive telescopes at locations that the weather has a minimum impact on the number of days they can view. Several of the larger concentrations of professional telescopes are high up in the mountains of Arizona. The high altitudes of the mountains reduce the amount of atmosphere required to view through, while the dryness of the Arizona countryside allows for the maximum number of days for viewing. Light pollution Light pollution reduces how dim any astronomical object can be. Man made light pollution is becoming a major problem to the amateur and professional astronomer alike.