3) how does air pressure change?

Air pressure decreases as you move higher in the atmosphere. Think of a column of air directly over your body. ... Just as air pressure decreases with altitude, so does the density of air.

Millibar values used in meteorology range from about 100 to 1050. At sea level, standard air pressure in millibars is 1013.2. Weather maps showing the pressure at the surface are drawn using millibars. ... This change in pressure is caused by changes in air density, andair density is related to temperature.

Aphysical change is one that you can put in and remove like a ham sandwich. the stuff you put in there can be changem its not permanet. a chemical change is on that can't be change thats permanet. like when you make a cake and bake it. you can't get those ingredients back.