FAA Aircraft Dispatcher Practice Exam

What is the purpose of an isobar?

1. To indicate altitude above sea level

2. To represent air temperature distribution

3. To show lines of equal pressure at sea level

4. To measure humidity levels in the atmosphere

The correct answer is: To show lines of equal pressure at sea level

An isobar serves to show lines of equal atmospheric pressure at a given level, typically at sea level. By connecting points of the same pressure, isobars provide a visual representation of pressure systems across a geographic area. This information is crucial for meteorologists and pilots, as it helps them understand wind patterns and weather systems. Areas where isobars are close together signify a steep pressure gradient, which often correlates with strong winds and turbulent weather. Conversely, widely spaced isobars indicate a more gradual change in pressure, suggesting calmer winds. While options that focus on altitude, temperature distribution, or humidity levels are relevant to meteorological studies, they do not accurately describe the specific function of isobars. Isobars are distinct from other lines on weather maps, such as isotherms, which indicate temperature, or humidity lines that reflect moisture content in the atmosphere. Thus, recognizing isobars is essential for interpreting weather patterns and making informed decisions related to aviation operations.