7. The major cause for variation in air pressure on the Earth's surface
is
A. the variation in specific heat of substances as they are
heated by the sun
B. the rotation of the Earth on its axis
C. the variation in the distance of the Earth from the sun
as it follows its orbit
D. the variation of elevation on the Earth's surface
the weather will be.

9.
The term relative humidity means
A. the percentage of water vapor mixed into the air
B. the percentage of water vapor in the air compared with
how much the air can hold when saturated
C. the temperature at which the air when cooled will
become completely saturated and start to condense
D. the point at which evaporation begins when the sun
shines on a body of water