system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do our joints ache when the barometric pressure changes?
gpt
Where two ends of the bones meet, they form a synovial joint. Basically a sac encloses the joint with fluid inside called synovial fluid. Low barometric pressure can increase the pressure inside of the synovial joint, indirectly increasing pressure on the ends of the bones.

EDIT: Someone rightfully corrected me, low pressure will cause the pain not high.