Final answer:
The term used to describe the challenge of visibility when facing bright light sources like direct or reflected sunlight during the day or car headlights at night is glare. Glare occurs when there is a significant contrast between the bright light source and the surrounding environment, making it difficult to see clearly.
Step-by-step explanation:
When facing bright light sources like direct or reflected sunlight during the day or car headlights at night, the challenge of visibility is referred to as glare. Glare occurs when there is a significant contrast between the bright light source and the surrounding environment, making it difficult to see clearly. Glare can be reduced by wearing sunglasses or using anti-glare coatings on surfaces such as car windshields.