Light availability refers to the amount of sunlight that reaches a specific area, which is crucial for processes like photosynthesis in plants. Factors affecting light availability include the time of day, weather conditions, and physical obstructions such as buildings or trees. In ecosystems, light availability influences plant growth and distribution, impacting the entire food chain. For example, in a dense forest, the upper canopy may block sunlight from reaching the understory, affecting the types of plants that can thrive there. This relationship is essential for understanding habitats and biodiversity in areas like tropical rainforests or savannas.