Final answer:
A tropical storm with wind speeds that swirl and can move up to 61 kilometers per hour is typically classified as a tropical depression. However, once a storm reaches sustained winds of 39 to 73 miles per hour, it is upgraded to a tropical storm.
Step-by-step explanation:
A tropical storm with wind speeds that swirl and can move up to 61 kilometers per hour is typically classified as a tropical depression. However, once a storm reaches sustained winds of 39 to 73 miles per hour, it is upgraded to a tropical storm. Tropical depressions have wind speeds between 25 and 38 miles per hour, and tropical storms have wind speeds between 39 and 73 miles per hour. These storms are characterized by swirling winds that rotate counterclockwise north of the equator and clockwise south of the equator.