Tornadoes can be a terrifying experience, but they can also be fascinating. The weather service describes tornadoes as whirling columns of air that may or may not touch the ground.
In Iowa, tornadoes are most common in the spring and early summer. But they can develop in the fall as well.
Wind shear is a type of change in wind speed or direction over a short period of time. Typically, this is caused by thunderstorms.
Storms produce wind shear because the winds in the lower part of the atmosphere, called the downbursts, move downward at a very fast speed and spread out in all different directions.
When this happens, it makes it more likely for tornadoes to form.
The two most important ingredients that tornadoes need to form are moisture and instability. Both of these are affected by climate change in one way or another.
For example, warmer temperatures can increase the amount of moisture in the air. But it can also reduce the availability of certain wind patterns that make severe thunderstorms possible. This can be especially the case in mid-latitudes where these thunderstorms are more likely to occur.
Moisture in the air is a key ingredient for tornadoes. This is because when humid air rises into thunderstorms, it cools and condenses to form cloud bases that are essential for tornadoes.
As the season transitions from winter to spring, warm, moist air masses push north into the United States. This creates a condition called the “inversion.”
The inversion prevents cold, dry air from spilling into the middle of the country and allows more warm air to move north. This helps increase the probabilities of tornadoes in the central part of the country.
Tornadoes are the most violent storms on Earth and typically kill 60 people per year. The majority of these tornadoes occur in a region stretching from Texas to Iowa, known as Tornado Alley.
Temperature determines the average kinetic energy of particles in the air. It also affects the speed of a storm's winds.
When warm air rises, it holds more water vapor than cool air. This means warmer weather causes more rain.
This rain can make Iowa's soils wetter and more susceptible to flooding. The rain can also cause groundwater to evaporate, leading to drought conditions.
There is a good chance that thunderstorms will produce tornadoes in Iowa. These storms often occur during the afternoon and evening hours.
The earliest tornadoes in Iowa usually occur in the spring or early summer. However, it is possible that a tornado could happen any time of year.
When a warm front reaches Highway 20 in eastern Iowa and a cold front reaches the area to its west, a triple point of warm air, cold air and a center of surface low pressure typically develops. This is a vorticity rich zone that favors tornado formation.
When thunderstorms form near this triple point, the updraft of the storm tilts the rotating column of air vertical. The result is a powerful tornado that rips through homes and crops leaving destruction in its wake.
In physics, the triple point is a temperature at which all three phases of matter (solid, liquid and gas) can coexist in equilibrium. It is a well-defined reference point for the calibration of thermometers.
During the 2022 tornado season, a series of tornadoes swept through central and eastern Iowa, killing at least six people and injuring several others. The tornadoes caused extensive damage, causing widespread power outages and flooding throughout the state.