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Ask the Meteorologist – Upward Lightning

ASK THE METEOROLOGIST

“What causes lightning to go up from the clouds, and what is it called?”

Aaliyah Linn

Grants Pass

Types of LightningThere are many types of lightning. The ones that we are all familiar with occur between the clouds and the ground or in between the clouds. However, there are more types out there. Some of these types of lightning shoot up from the cloud. These are a little more rare and happen more quickly. Therefore it is a little bit harder to get a clear picture of them.

Here are some types of upward lightning:

Cloud-to-Air:

ctaCloud to air is probably the most common type of lightning that moves from a cloud upward. It is only more common because it lasts the longest and is the brightest, making it easier to see with the unaided eye. The positively charged cloud needs to transfer energy to something around it that is negatively charged. Usually this is the ground or another cloud. However, sometimes the atmosphere immediately around the cloud is negatively charged. This causes the cloud to transfer its positive energy to the surrounding air. This is known as cloud-to-air lightning.

Another way that cloud-to-air lightning can form is when a stroke is meant to reach to the ground or another cloud, and the return stoke does not meet it. Basically, when lightning hits the ground or another cloud, the initial stroke extends from the thunderstorm. However, a “return stroke” must meet it. This return stroke comes from the object that the lightning is about to strike. Sometimes, when a stroke of lightning extends from a thunderstorm intending to hit another cloud, the “return stroke” from the other cloud does not make it and the lightning bolt stays in the surrounding air. This is another form of Cloud-to-air lightning.

Sprites and Elves:

spritesAnother type of lightning that shoots upwards from a cloud is called a sprite. Sprites are a glow that is usually colored red at the top and vary to purple and blue towards the bottom. Sprites are caused by other lightning. Some of the most intense lightning occurs when a thunderstorm is in its mature phase. When a very strong cloud-to-ground lightning strike occurs, some of its built up energy sets off a spark, usually about 45 mi above the ground. Energy (in the form of light streamers) is sent in all directions. Usually this occurs near the top of a cloud so the only ones visible are the streamers that move upwards. This is known as a sprite. Sprites can be seen with the naked eye but are extremely rare; not only because of the length of time they last (less than a hundredth of a second), but also because they only occur from certain types of thunderstorms.

elvesElves also occur from a built up cloud-to-ground lightning strike. Sometimes they occur with a sprite, and sometimes they occur by themselves. When a lightning strike occurs with enough energy, it creates an electromagnetic pulse (EMP) in the upper level of the atmosphere that causes the upper level gasses to glow. Once the elve occurs, it scatters from the center in a halo-like fashion and can travel for hundreds of miles. These are also rare to see and photograph because of the even shorter life span of less than a thousandth of a second.

Blue Jets:

Blue JetBlue jets are another type of upward lightning. Unlike sprites and elves, blue jets do not have any association with other lightning strikes. Instead, blue jets are sent upwards from storms that usually have an active tornado or will soon have one. They usually occur at the upper most portion of a thunderstorm. They also tend to occur in storms that have a higher than average number of lightning strikes. These blue bolts can be seen with the unaided eye and tend to have a longer life span of about a quarter of a second.