Examples of reflection. Plane wave, plane surface. The phase of the reflected sound waves from hard surfaces and the reflection of string waves from their ends determines whether the interference of the reflected and incident waves will be constructive or destructive.
The tendency to develop allergies is often hereditary, which means it can be passed down through genes from parents to their kids. But just because you, your partner, or one of your children might have allergies doesn't mean that all of your kids will definitely get them, too.
Allergies can either be seasonal or perennial. Seasonal allergies, such as hay fever, occur at specific times of the year, while perennial allergies can occur throughout the year. Allergies can affect various parts of the body, and symptoms are particularly common in the eyes, nose, throat, and lungs.