What is a storm and how does it form – 12/14/2023 – Science

What is a thunderstorm? The apparently simple question to answer is among those that saw the biggest increase in searches made by Brazilians in 2023 on Google.

According to the company, there has never been so much research into this natural phenomenon in Brazil since the beginning of the historical series, in 2004.

Searches for the term “storm” grew by more than 50% compared to last year and more than 70% in the last three years.

Residents of the southern region of the country —Santa Catarina, Rio Grande do Sul and Paraná— were those who were most interested in the topic.

Between the 12th and 18th of November was the period in which the questions reached a record high, being the week in which the most Brazilians became interested in the subject.

It was precisely during this period that the southern region of the country faced winds of up to 80 km/h and above-average rainfall due to the El Niño phenomenon.

According to the National Institute of Meteorology (Inmet), the rains intensified and caused several problems such as flooding and floods in cities in Rio Grande do Sul and Santa Catarina, mainly.

Rising surveys show that Brazilians also have a lot of doubts about how a storm forms and in relation to everyday situations, such as whether they can use a cell phone or even take a shower.

Check out the questions asked on Google below about one of the most popular topics in Brazil in 2023, answered by experts interviewed by BBC News Brasil.

1. What is a thunderstorm?

A storm is a meteorological phenomenon that “has the characteristics of strong winds, rain, thunderstorms, lightning, hail and lightning”, explains Paulo Cezar Mendes, professor of climatology at the Federal University of Uberlândia (UFU).

In other words, it is heavy rain with lightning or hail — rain that does not have at least one of these phenomena is not considered storms.

Thunderstorms form in large vertical clouds, called cumulonimbus.

Milder rains are formed in clouds cirrus (fibrous, tall, white and thin) or stratus (clouds with less shape, which are a little lower in the sky).

The type of cloud that is formed is what determines the intensity of the rain, the time it will take to fall and, consequently, whether it is a storm or not.

2. How does a storm form? What causes a thunderstorm?

Although these are different questions, they are similar, and the answers complement each other. So, let’s answer them together.

A storm is a meteorological phenomenon characterized by a lot of atmospheric instability, which causes the molecules present on the Earth’s surface to move very intensely, causing the formation of clouds.

They form from the movement of air in an area of ​​low atmospheric pressure.

“The storm is mainly associated with the meeting of two air masses with different characteristics (hot/dry and humid/cold) which causes a variation in temperature in the atmosphere. This shock causes an intense movement of the molecules present on the surface of the earth and this agitation”, explains Rafael de Ávila Rodrigues, professor and climatologist at the Institute of Geography at the Federal University of Catalão (UFCAT).

“In other words, the hot air (less dense) rises into the atmosphere, while the cold air (more dense) descends towards the ground surface, providing a reduction in atmospheric pressure”, explains the climatologist.

“This collision between air masses is what causes the storm.”

3. How does a storm happen?

A storm is a meteorological phenomenon characterized by a lot of atmospheric instability, that is, when the sky is “agitated”.

Instability occurs when molecules present on the Earth’s surface move very intensely, causing the formation of clouds.

They form from the movement of air in an area of ​​low atmospheric pressure.

“The storm is mainly associated with the meeting of two air masses with different characteristics (hot/dry and humid/cold) which causes a variation in temperature in the atmosphere”, explains Rafael de Ávila Rodrigues, professor and climatologist at the Institute of Geography from the Federal University of Catalão (UFCAT).

“In other words, the hot air (less dense) rises into the atmosphere, while the cold air (more dense) descends towards the ground surface, providing a reduction in atmospheric pressure”, explains the climatologist.

“This clash between air masses is what causes the storm, because it causes intense movement of molecules and this agitation”, he states.

4. How long does a storm last?

The duration of a storm can vary from a few minutes to several hours.

The determining factor for this is whether it rains hail (ice) or not. Rain with hail is more common on very hot days.

It happens when warm air from the Earth’s surface encounters very cold clouds at higher points in the atmosphere. The sudden contrast in temperature causes the water droplets to solidify, forming hail. Ice rocks form in clouds of great vertical extent, called cumulonimbus.

When these clouds can no longer support the weight of the ice rocks inside them, they collapse all at once, forming hailstones.

Storms with hail last, on average, 10 to 30 minutes, explains Mendes.

“Because the cloud forms and it quickly discharges all the energy contained in it in the form of a storm”, says the UFU professor.

Other forms of storms without hail are formed in clouds that spread over larger areas and discharge more slowly, lasting from an hour to an entire afternoon, adds Mendes.

“It is precisely this large accumulation of water that can cause problems, such as floods and flooding.”

5. What to do in a lightning storm?

Lightning is an atmospheric electrical discharge that originates from a cloud and strikes the ground or another cloud.

It is formed within vertical clouds, the ones that cause storms, from the attraction between opposite charges (positive and negative) that are present in them.

Positive charges are at the top of the cloud and negative charges are at the bottom. This difference in charges generates lightning, which releases this energy charge, which can reach the ground.

Thunder is the noise generated when this discharge of energy (lightning) passes through the air. And lightning is the electromagnetic radiation produced by the plasma that forms in the air when the lightning (the discharge) passes – part of this radiation is visible light, that is, it is the “flare” that we see in the sky.

When there is lightning in a storm, the recommendation is not to stay in open places. The best thing to do is always protect yourself.

“The first thing is to look for shelter, whether in a property or in a car,” says Mendes.

But, if this is not possible, there is a way to minimize the risks of being struck by lightning, such as not staying close to trees, for example.

“You should avoid staying under trees, because lightning seeks the shortest distance between the cloud and the ground”, says the climatologist.

“In this case, it is recommended that the person sits or lies on the ground to prevent the body from turning into a lightning rod.”

6. Can I use my cell phone during a storm?

Experts interviewed by BBC News Brasil say that the risk associated with using a cell phone during a storm actually depends on the situation in which each person finds themselves.

“If you are in a sheltered environment, inside your home or car, and your cell phone is not plugged in, there is no problem using the equipment”, explains Mendes.

But, if a person has the device plugged in, the specialist’s recommendation is not to use it or to remove it from the socket to use it.

“Lightning could strike this electrical network and reach your device, causing an accident, such as an electrical discharge”, adds the UFU professor.

And in cases of open, open environments or at high altitudes, such as hills and mountains, the recommendation is also not to use the device because it can become a lightning rod — also causing an electrical discharge.

7. Can I shower during a thunderstorm?

The danger associated with taking a shower depends on the shower a person has at home, according to experts.

The electric shower, as the name suggests, is an energy conductor.

During storms, it is not recommended to use or be in contact with equipment that works with electricity in general.

“If lightning hits the power grid and is not blocked by the house’s circuit breakers, it can hit the shower and cause an electric shock to anyone in the shower,” explains Mendes.

This electrical discharge can cause skin burns or cardiac arrest and can even lead to death due to the electrical shock.

However, if the shower is not connected to the mains, such as those supplied by a heater, there is no problem using it during a storm.