Which two unusual phenomena typically occur in high-rise buildings?

In high-rise buildings, two significant phenomena that occur are stratification and the inverse stack effect.

Stratification is the process where hot air rises and cool air settles, leading to distinct layers of temperature within the structure. As fires generate heat, the air above the source becomes much hotter than the air below it, which can create hazardous conditions for firefighters. This layering effect affects visibility and can complicate fire attack strategies, as it alters how smoke and heat behave in the building's interior.

The inverse stack effect refers to a situation in tall buildings where, typically in the winter, colder air moves down from the upper floors and into the lower levels. This occurs when the air inside the building is heated, causing it to rise and exit through upper openings. As a result, colder outside air enters the lower openings to replace it, which can enhance the spread of fire and complicate ventilation efforts.

Understanding these phenomena is crucial for effectively managing fire scenarios in high-rise buildings, as they influence the behavior of smoke and heat, impacting both evacuation and firefighting operations.