Above the alcohol surface there is air, mixed with alcohol vapour. The alcohol is in thermal equilibrium with its saturated vapour. When the lower part of the container gets warmer, the equilibrium changes and the pressure of the vapour above the liquid rises. The pressure, which is higher than the pressure in the upper bulb, forces the liquid upwards. The warmer the hand is, the quicker the liquid rises.

When you hold the lower bulb of the thermometer, and your hand is warm enough, the colourful liquid will rise shortly after, and indicates what temperament you have. If you keep in hands both upper and lower container, the pressure rises in both of them and hardly the liquid moves up or down.