Seeing: Telescopes on La Palma

One of the things that I really wanted to see in La Palma was the collection of telescopes. Turns out that they are perched high on the rim of the gigantic caldera. I finally spotted them through binoculars! They are high on the mountain because they get better "seeing". Stars twinkle because of the motion of layers of air in the atmosphere. Even on cold nights there is often a lot of convection round here as the land cools down. Air of different temperatures means different refractive indices so images get bent and then move as the layers move - there's the twinkling. The higher you are, the less air above so the less distortion. The volcanoes in the Canaries poke out above the main cloud layer. There is also little light pollution because so few people live on La Palma. The views are simply better.