To find causal relations between human hemodynamics and changes of the atmospheric pressure (AP), a computer based multilevel mathematical model is proposed. The model connects the functional state of cardiovascular system (CVS) with its summary blood volume that in its turn depends on fluid volumes in compartments presenting the lymphatic, the intercellular and the summary cellular systems. It is assumed that the current values all of these volumes can be modulated by changes of AP. Additional to biophysical processes, the complex model also describes the excretory function of kidneys and the mechanoreceptor control of CVS. Computer simulations illustrate the liquid dynamics in all presented compartments under double-side slow but long term essential shifts of AP. The simulation data can be used to better understand the role of APviolations in human meteo-sensitiveness.