Answer:
Earth's Upper Atmosphere. And Volcanoes.
<span>Personal protective equipment is only helpful if regulations for using it are followed carefully. If it is not worn and used properly, then it will not function properly and it might not provide the protection that is needed in the situation. For example, a helmet is only effective if it is fitted properly and snugly on the head. Otherwise it could fall off in an accident and be rendered useless.</span>
Distance between corresponding points 2 consecutive waves
