Which of these nozzles is NOT used for creating broken streams?

The fog nozzle is designed to produce a wide spray of water droplets that enhances cooling and provides better coverage over a larger area, which is beneficial for firefighting in various scenarios, particularly in structures. Its function is to create a fine mist and distribute water effectively, allowing for improved vaporization and cooling.

In contrast, the other nozzles listed—cellar, rotary, and piercing—are specifically engineered to create broken streams of water. The cellar nozzle delivers water in a manner that helps it reach below ground levels, making it useful for tackling basement fires. The rotary nozzle utilizes rotation to create an effective broken stream that can penetrate deeper into the fire. The piercing nozzle is designed to pierce exterior surfaces such as walls or roofs, allowing firefighters to direct water onto the fire from a distance.

Each of these nozzles effectively disrupts the water stream to maximize penetration and reach, which is not a characteristic feature of the fog nozzle. Thus, it clearly stands out as the option not utilized for creating broken streams.