Here's why:

* Formation: Lightning is caused by the buildup of static electricity within a storm cloud. This happens when different types of water particles (ice crystals and hailstones) collide within the cloud, creating a separation of electrical charges.

* Discharge: The negative charges gather at the bottom of the cloud, while positive charges accumulate at the top. This creates a strong electrical potential. When this potential becomes too great, it discharges in the form of lightning.

* Ground Connection: Lightning can strike the ground because the ground has a positive charge. The negative charge in the cloud seeks a path of least resistance to reach the positive charge, and this path often leads to the ground.

So, while lightning can strike the ground, it originates from the cloud and travels towards the ground.