Ultrasound refers to a sound wave with a frequency greater than the upper limit of human hearing, which is generally over 20 kHz. In general, humans can hear sounds with a frequency between 20 Hz and 20 kHz.
Lake Ontario is one of the five Great Lakes of North America. It is bordered by the Canada and United States. It is the only Great Lake not to border the state of Michigan.
The Stratosphere is the layer of the Earth’s atmosphere which lies beyond the troposphere. It extends up to an altitude of 50 kilometres from the earth’s surface. This layer is almost free from clouds and associated weather phenomenon. It therefore makes conditions most ideal for flying aeroplanes.
EXAMIANS