Mauna kea hosts the largest concentration of cutting edge observatories in the world there are several reasons for this...

1) Hawaii is an island on the pacific, the winds over the pacific are low in turbulence when they hit hawaii after passing over the smooth ocean.

2) Mauna kea is ~14,000 feet high- this puts you above a lot of clouds and atmosphere- cloudy nights happen on MK but are not the norm...

3) MK is a very gently sloping mountain, it doesnt create a lot of turbulence as the winds slide over it.

There have been seeing studies that indicate MK is the best place in the _world_ for astronomy...

ANYWAY, the cities around MK use sodium streetlights with covers that reduce upward scatter... the telescopes can filter out the sodium light with rejection filters- looking out on the island at night from the summit the cities glow yellow/orange from the sodium vapor lights...

I am amazed that the whole island has adapted to help astronomy- but with 10+ telescopes on the summit all of which bring a lot of money to the island maybe it makes sense.

MK is the obvious place for the next generation scope- the 30 meter scope... but sadly it is almost certain not to happen- MK is a source of political strife- I wont go into the details, they are too sordid... Most likely the 30 meter will end up in the canary islands or south america...