What is Glare in Light Pollution?
In the context of light pollution, glare is defined as excessive brightness that causes visual discomfort.
Glare is one of the primary forms of light pollution, characterized by light that is too bright for the surrounding conditions. When light sources are excessively bright, they can interfere with vision, causing discomfort and potentially reducing the ability to see clearly. This discomfort is often experienced as a dazzling sensation or an uncomfortable brightness in the field of vision.
According to the provided reference, components of light pollution include:
- Glare — excessive brightness that causes visual discomfort.
- Sky glow — brightening of the night sky over inhabited areas.
- Light trespass — light falling where it is not intended or needed.
- Clutter — bright, confusing, and excessive groupings of light sources.
While other forms of light pollution impact the environment, sky glow, or distant astronomical observation, glare directly impacts human vision and safety, particularly at night.
Types of Glare
Glare can manifest in several ways:
- Disability Glare: This is the most severe form, causing a significant reduction in visibility. It often occurs when extremely bright lights are present in the field of view, effectively blinding the observer temporarily (like oncoming headlights on a dark road).
- Discomfort Glare: This causes visual discomfort but does not necessarily impair visibility severely. While less dangerous than disability glare, it can still be irritating and distracting.
- Veiling Glare: Occurs when light is scattered within the eye itself, reducing contrast and making it harder to see details.
Impacts of Glare
Excessive glare from poorly designed or aimed outdoor lighting has various negative impacts:
- Reduced Visibility and Safety: Glare can temporarily blind drivers, pedestrians, and cyclists, increasing the risk of accidents. It makes it harder to see obstacles or changes in the terrain.
- Visual Discomfort: As the definition states, glare causes discomfort, eye strain, and fatigue, especially during nighttime hours.
- Impact on Wildlife: Bright, glary lights can disorient nocturnal animals, disrupting their navigation, hunting, and breeding patterns.
- Aesthetic Nuisance: Glare can detract from the beauty of the night sky and the environment.
Minimizing Glare
Addressing glare in outdoor lighting design is crucial for mitigating light pollution and improving safety and comfort. Effective solutions include:
- Using Fully Shielded Fixtures: These fixtures direct all light downwards, preventing light from escaping horizontally or upwards towards the eye.
- Lowering Light Levels: Often, less light is needed than initially thought. Using appropriate light levels for the task reduces unnecessary brightness.
- Aiming Lights Correctly: Ensuring lights are directed only where needed and not towards observers' eyes.
- Choosing Appropriate Color Temperature: Warmer color temperatures (lower Kelvin values) tend to be less harsh and cause less glare than cooler, bluer lights.
- Implementing Smart Lighting: Using motion sensors or dimmers so lights are only at full brightness when necessary.
By understanding what glare is and its impacts, we can design and implement lighting solutions that provide necessary illumination without causing visual discomfort or contributing negatively to light pollution.
