We see lightning most frequently in the summertime due to the season's high temperatures. When the ground heats up to become hotter than the surrounding air, the air rapidly rises. As the air rises to cooler temperatures, it condenses into moisture, and accumulates to form a cumulonimbus cloud. This formation of cumulonimbus clouds is a good sign that the fascinating process of lightning has begun.

The countless water droplets and ice crystals that make up a cloud are in a continuous process of condensation and evaporation. Moisture collides as it rises, falls, and collects at the bottom of the cloud. Colliding moisture molecules produce electrons and, as a result, a cloud becomes positively charged in the upper region and negatively charged in the lower area. While it is not certain how the charge becomes separated, scientists have come up with a plausible explanation.

When moisture molecules collide, electrons are "bumped off." The moisture that loses an electron continues to rise to the top of the cloud, carrying a positive charge. The "knocked-off" electrons gather at the lower part of the cloud and create an area with a negative charge. This is called a "charge separation." As positively charged moisture rises into colder temperatures, some of it begins to freeze. This frozen moisture becomes negatively charged, while the unfrozen droplets remain positively charged. Once frozen, the negatively charged droplets fall towards the bottom of the cloud. Through this process, clouds end up with an extreme separation of charges and an electric field.

It is this electric field that instigates lightning. The electric field in a cloud is divided with a negative field in the lower region and positive field in the upper region. The intensity of these fields depends on the charge build-up. When the buildup is severe, and the cloud's lower portion carries a strong negative charge, electrons on the earth's surface repel deep into the ground creating a strong positive charge.

It is Nature's way to neutralize this charge separation. This is accomplished through an electrical discharge of current that we call lightning. However, before lightning can strike, before these positive and negative charges can come in contact, a conductive path is needed. Ionizing air creates "plasma steps" towards the earth. These paths are formed in areas with the least resistance, which causes it to be jagged (that's why we don't see lightning in straight lines). A complete conductive path is created between earth and a cloud once the plasma formation reaches the earth's surface. This provides the final direction to where lightning will travel, and completes nature's exciting course from cloud formation to the electrical phenomenon we know as lightning.

A bolt of lightning has an incredible amount of energy and results in an enormous amount of heat. The heat is so intense that it is actually hotter than the surface of the sun. That is why there is a white-blue flash associated with lightning bolts. Air surrounding the lightning bolts becomes extremely hot, making molecules move so fast that the air actually explodes due to the rapid expansion of air. This explosion is known as thunder and we hear after we see the lightning because sound doesn't travel as fast as light.