What is the purpose of using flares at sea?

The purpose of using flares at sea primarily aligns with signaling distress to other vessels. Flares are specifically designed as emergency signaling devices used to alert nearby boats or aircraft to an emergency situation. When a vessel is in distress, launching a flare can effectively communicate that immediate assistance is needed, drawing attention to the exact location of the incident.

While the other options touch on different notions such as navigation or weather conditions, flares are not typically employed for those purposes. Flares do not provide adequate light for navigation or effectively indicate weather conditions, though they can be seen from a distance. The function most associated with flares is their ability to signal distress, which is fundamental for safety and search and rescue operations at sea.