If starting out in astronomy , you may have heard of cooling down times . So what does this mean, and what are the benefits.
When you first take a telescope outside in to the cool night time air, the scope will remain warm for a while. The warm air off the scope will rise , and cause turbulent air currents. As a result it seem as if you are looking through rippling water. This can make the image very unsteady, and will increase with higher power magnifications.
A way to help reduce this is to let your scope cool down (cooling down time). By having your telescope the same temperature as outside, there will be less warm air rising, and so help reduce the turbulence and make the image more steady.
Cooling down times can vary from one scope to another. For example an enclosed SCT telescope will take longer to cool down when compared to a similar sized open tube reflector for example.
To help combat this issue many scopes come with, or can be fitted with cooling fans.
You will find that once your scope is cooled down, the cold winter evenings will give you the better views compared to the warm Summer evenings
The cooling down technique is not just for astronomical telescopes. Exactly the same applies to binoculars and spotting scopes.