Continue reading the main story. Hundreds of pages of sworn testimony by Mr. Trump over the past decade show something less flattering. Some of his claims, made under oath, and under pressure, are shown to be hyperbolic overstatements, and others to be shadings of the truth or even outright misstatements. And in rare instances, he turns boorish and demeaning.
There are two types of sonarâactive and passive. Sonar, short for Sound Navigation and Ranging, is helpful for exploring and mapping the ocean because sound waves travel farther in the water than do radar and light waves. NOAA scientists primarily use sonar to develop nautical charts, locate underwater hazards to navigation, search for and map objects on the sea floor such as shipwrecks, and map the sea floor itself.
Sonar uses sound waves to 'see' in the water. A three-minute video about multibeam and side scan sonar, including a visualization that shows how sonar data is used to make products like nautical charts. | Download: Soundscapes (75 MB).