The heat on the outside of the thermometer transfers to the glass which transfers to the alcohol making the alcohol expand making it rise

Alcohol in a thermometer rises whenever the temperature of its surrounding increases. As the temperature increases, the heat causes the alcohol to expand ever so slightly, which shows up as an increase of height of the alcohol in the tube of the thermometer.

u don't have to flick the thermometer to reset the temperature reading when you use an alcohol based thermometer (unlike a mercury thermometer where you have to flick and flick and flick flick flick that thermometer for the mercury to be reset so that you can make an accurate reading) a disadvantage is that the alcohol thermometer is slightly less acurate The biggest advantage is that alcohol is not nearly as toxic as mercury, so that if the thermometer breaks, you won't be poisoned.

it does not stick the wall of thermometer

it expand regularly

Mercury and alcohol