More examples by category and region (work in progress)
The unshielded bright lights available to commercial/industrial and residential developments can be easily seen for miles. Therefore, light pollution must be addressed both in the design of industrial and commercial facilities (which generally need more light than residential) and at the level of residential dwellings (which need less light but exist in greater numbers). This section presents good and bad examples of lighting. All commentary is in regard to the lighting and doesn't reflect on the quality of service of any business or institution that may be portrayed here.
Commercial and Industrial
Car lots are often cited for their excessive lighting. To put matters in perspective, it is a pleasure to have local dealerships, and these dealeships are entitled to a reasonable use of light. The question how much and whethe the same lights uses to show their products need to be the same lights left on all night for security. Below shows two areas with different lighting. The left is of Rancho Ford's service area. The use of low pressure sodium lights (yellow) is a delightful step in the right direction.
Roof Lighting: Denny's, Temecula
Lighting a roof arguably has little value in providing safety and security. In the case of Denny's in Temecula, their roof lighting is excessive.
The photograph below shows the Denny's in Temecula and their roof lights. Each light puts out a wide beam. Denny's uses 14 of these wide-angle, high intensity floodlights. On the far right, you can see the flare from one of these lights. Considering that the photograph is taken on an embankment above the building and off to the side by about 45 degrees, you can appreciate the wide field of these lights. Much of the light being used misses the roof and creates glare and light pollution instead.
A spokesperson for Denny's defends their lighting as necessary for attracting customers (See Press Enterprise, Let There Be Night). Palomar Observatory, and perhaps Dennys too, would be better served by recognizing that the food and service draw the customers and the roof lighting is merely overhead. Real safety and security is provided by Temecula's police, fire, and ambulance services, which make all-night businesses possible.
Much light pollution would be eliminated merely be ensuring that lights do their job well. For example, the purpose of the flood lighting shown below is to protect property or provide visibility. But it does either of these poorly.
First, whether it protects the driveway or vehicles parked there from theft or vandalism is debatable (I have numerous examples of theft and vandalism occuring in the presence of flood lighting). And second, it creates enough glare to be a nuisance and safety hazard, which undermines its benefit. Note that the light is cast upward and outward as well as downward. Lighting the trees across the street provides no deterence to theft or vandalism, and is a waste of energy. But more relevent to a residential neighborhood with children, it creates glare that can impair a motorist's ability to see a rock in the street or a child on foot, on a skateboard, or on a bike. Cameras tolerate glare better than the human eye, so the following photos will show objects clearly, but use the next two photos in sequence to get an idea of how your vision would respond to the sudden appearance of the light from behind the tree.
Visibility is good here for both the camera and the eye, because the tree effectively sheilds the light. But as soon as you drive out of the shadow of the tree, the light is like a stab in the eyes.
At this point, the motorist's eyes are adapting to the brightest light -- the flood light. The pupils are contracting and the faint light from pedestrians is overwhelmed by the glare. This is similar to the approach of another car's headlights. The difference here it that lights like this become permanent fixtures, always interfering with seeing. I know of numerous intersections where left and right turns are hazardous because there is always an unshielded light in the way of the where I need to look to make a safe turn. The solution is simple. Shield the light with a viser so that it lights only the driveway and sidewalk. This shielding would allow the light to perform its function without the nuisance and hazard of glare, which in turn reduces light pollution.
The typical stock light with new homes lacks any shielding. Most of the light falls upward and on the neighbor's property (including in their bedroom windows). A more night-sky friendly and neighborly solution is below.