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tropical depression vs. tropical storm

tropical depression
[trop-i-kuhl di-presh-uhn] / ˈtrɒp ɪ kəl dɪˈprɛʃ ən /

noun

Meteorology.

  1. an atmospheric low-pressure system originating in the tropics, specifically, a tropical cyclone in which the maximum sustained wind speed is 38 miles per hour (62 kilometers per hour) or less.

tropical storm

noun

Meteorology.
tropical storms plural

  1. a tropical cyclone of less than hurricane force.