Many of the images you find here were taken in La Palma, at the Roque de los muchachos observatory (ORM), at an altitude of about 2300m. The Roque is one of the darkest spots at night left on Earth, and hosts a number of international institutions who built their telescopes there.
During summer the seeing is often very good, and temperatures are very agreeable. During winter, the Roque can let you feel the forces of nature to the most terrifying levels, since the tiny island of La Palma is not really an obstacle for a full-blown storm system on its way over the atlantic ocean. Transparency is usually very good, but often hampered by dust storms coming from the Sahara desert.