What is a defining characteristic of acute hypothermia onset?

Acute hypothermia is primarily characterized by a rapid onset, often triggered by sudden exposure to cold conditions, especially cold water. When a person is exposed to cold water, the body can lose heat much more quickly than in cold air due to the higher heat conductivity of water. This rapid cooling can lead to a significant drop in core body temperature in a very short period, making it a critical situation that requires immediate attention.

The defining feature here is the speed of onset caused by cold water exposure, which is much more dangerous than other scenarios where the onset might be slower, such as gradual exposure to cold air over several days. In acute scenarios, recognizing the signs of hypothermia quickly is vital for effective management and treatment.