You check a barometer and observe that the air pressure has been dropping all day. Is tonight's weather more likely to be calm or stormy?

If you had been checking the barometer and observe that the air pressure has been dropping all day, tonight's weather more likely to be stormy. Stormy weathers have low pressure climate

The weather will be stormy if the barometer is showing decreasing readings all day, this is because a low pressure system forms as the Eye of the Storm takes all the wind away creating a high pressure zone so the storm moves in the direction of the low pressure zone.