During a light storm, what can cause the ground to become positively charged?

The charge in the clouds can cause the ground to become positively charged.

Explanation:

During a thunderstorm, the important charging area is the central part or portion of the storm when air is moving in an upward direction. The temperature here ranges from -15 to -25 degree Celsius.  The ground has a slightly negative charge and when a thunderstorm comes the negative charge on the ground is repelled by the negative charge in the center of the storm. This makes the ground that is underneath the storm to become more positively charged.  

"the periodic table is arranged in order of atomic number."