The character of a pressure change is determined based on the observed change over which time frame?

The character of a pressure change is typically assessed over a 3-hour period because this timeframe allows meteorologists to identify trends and patterns in atmospheric pressure that can indicate changes in weather conditions. Observing pressure changes within 3 hours provides enough temporal resolution to determine whether the pressure is rising, falling, or remaining steady. This short-term observation is crucial for making forecasts about impending weather phenomena, such as fronts or storms.

While longer time periods can show trends, such as a 24-hour observation which might indicate broader climatic changes, the 3-hour observation is particularly valuable in forecasting. It keeps pace with the rapid developments often encountered in meteorology, especially in the context of severe weather. Thus, using a 3-hour window is standard practice among meteorologists when analyzing weather data and making forecasts.