What color smoke does a submarine emit to indicate that a torpedo has been fired?

The correct answer is that a submarine emits black smoke to indicate that a torpedo has been fired. This practice is rooted in the need for clear communication and recognition of actions taken during naval operations. The black smoke serves as a signal to nearby vessels and aircraft, indicating the launch of a torpedo, which is a serious action and requires immediate awareness from other maritime traffic.

Using black smoke as a signal is important for safety and operational integrity. It distinguishes this specific action from other operations that may use different colors for signaling purposes. For instance, red smoke is often used as a distress signal, while white could be related to other non-threatening communications. Green might indicate a safe condition or go signal in various maritime contexts, but it does not pertain to the firing of torpedoes. Thus, the association of black smoke with the firing of a torpedo is significant for operational clarity in naval engagements.