a. Listening to the weather report, you hear that the barometer is falling. What part of the barometer is falling?
The level of mercury is falling.
b. What is happening to the air pressure?
The air pressure is decreasing.
I agree.
To understand why the barometer indicates a falling barometric pressure, we need to understand the basics of how a barometer works.
A barometer is a scientific instrument used to measure atmospheric pressure. It consists of a long glass tube filled with mercury and inverted into a container filled with more mercury. The pressure exerted by the air on the surface of the mercury in the container causes the mercury in the tube to rise or fall. The height of the mercury column in the tube is a measure of the atmospheric pressure.
When the weather report mentions that the barometer is falling, it means the level of mercury in the barometer tube is decreasing. This decline in the mercury column indicates a decrease in atmospheric pressure. In other words, the air pressure in the atmosphere is dropping.
As air pressure decreases, it suggests that there might be a change in the weather conditions. Falling barometric pressure indicates the approach of a low-pressure system, which is typically associated with cloudy, rainy, or stormy weather. It can be an indicator that a weather front is approaching or that the current weather system is weakening.
So, when the weather report mentions a falling barometer, it informs us that the level of mercury in the barometer, which represents the atmospheric pressure, is decreasing. This decline in air pressure can foreshadow changes in the weather.