Houston is the 4th largest city in the U.S. and one of the more common places for lightning.

Geographically, Houston boarders Galveston Bay/Gulf Of Mexico to the northwest.

Houston’s climate is a humid subtropical, that is fed by heat from the deserts of Mexico and moisture from the Gulf of Mexico.

Summers are very hot and humid, winters a cool with no snow and some rain.

June – August Houston averages 1,700 ground flashes a month.

Houston through yearly seasons can accumulate anywhere from 40%-70% more cloud-ground lightning strikes than the surrounding country lands.

Dr. Richard Orville of Texas A&M University and others, have researched and proven many case studies over the years that all support the effects believed to be behind the enhancement of lightning over Houston.

3 Common Theories to Lightning Enhancement over Houston

1) Impact of Urban Heat Islands

2) Air pollution

3) Oil refineries

Urban Heat Island Impact

Urban Heat Island effect is the rising of warm pockets of air, due to the reflection of the Sun’s rays off of the concrete ground.

The idea of this is, warm air converging with the sea breeze of the Gulf in an upward motion, makes the atmospheric conditions favorable for thunderstorms to produce.

In support of Houston’s urban heat island influence,

Orville modeled Houston’s land area with a city and one without a city, both with low-level convergence. After testing, the results showed that the circulation pattern was much stronger in the model with a city. This convergence triggered convection cells, where as the no-city model experienced no convection. This shows that the low-level sea breeze itself is not enough to create convection.

What happens in Houston?

The warmer air from the city rises when thecool air from the sea is pushed in, and this is why large clouds capable of thunderstorm activity produce.

Oil Refineries Impact on Houston

49% of the U.S. petroleum refining capacity is located in the Houston area.

So what’s the idea here?

The oil refineries surrounding Houston are releasing a large number of aerosols into the atmosphere. These aerosols are then joined by the already present pollution from the city causing favorable atmospheric conditions for a thunderstorm.

Orville’s Discovery,

Dr. Orville made a bizarre connection between Houston and Lake Charles, Louisianna. After thinking about the two similar patterns of lightning occurance for both cities, Dr. Orville realized that Lake Charles was also home to much of the U.S. oil refineries. In turn this supported his idea that the increase of aerosol loading in Houston and other urban areas is one contributing factor for enhanced lighting activity.

Hazard Maps For Lightning Frequencies in Both Cities

1989-2000 Mean Annual Flash Density

(Flashes km^2 yr^1) For Houston, TX

1989 – 2002 Mean Annual Cloud to Ground Flash Density

(Flashes km^2 yr^1) For Lake Charles, LA

Impact of Air Pollutions

What it does,

Helps moisture rise into the upper atmosphere.

This allows for these water molecules to collide with ice crystals, thus creating electricity from the friction.