A tornado is a rapidly rotating column of air that is simultaneously in contact with the surface of the earth and the basis of cumulonimbus. Tornadoes reach different sizes. They usually take the form of a visible condensation hopper with a narrower end of the touching ground. The lower part of the funnel is often surrounded by a cloud of debris and dust.
Tornadoes have been observed on every continent except Antarctica, but the most tornadoes are recorded in the United States annually. Most tornadoes have a wind force of no more than 180 km / h, a hopper width of up to 75 meters, and it stays in contact with the ground long enough to cover a few kilometers on its surface. Some have a wind speed of over 500 km / h, a hopper width of 1.5 km and travel to 100 km. The strength of tornados is measured on the Fujita scale. Most of the most destructive tornadoes are formed in storm clouds called supercells. Not everywhere, this weather phenomenon gains strength enough to be called a tornado. It is usually referred to as the „whirlwind„. The strongest tornadoes to date occurred: May 20, 2013 in the cities of Moore and OklahomaCity, and May 31, 2013 in El Reno.
Tornadoes can have different colors depending on where they are made. Tornadoes created in dry conditions may be invisible in addition to rotating debris at the surface of the earth. A condensation hopper that raises little dust and debris can be gray or white. When moving over water, tornadoes can take on a white or blue color. Pours moving slower and sucking in many shards are usually dark and take on the color of the material being conveyed. Tornadoes on large plains often take on the red color due to the color of the earth, and whirlpools passing over mountain areas can be snow white because of the presence of snow.
Lighting is the main factor in the appearance of a tornado. The tornado that is backlit by the sun looks very dark, while the same tornado observed when the sun shines in the observer’s back may look gray or white. Tornados occurring at sunset can take shades of yellow or red.
Dust raised by wind, intense rain or hail and darkness are factors that reduce the visibility of tornadoes. Tornadoes in these conditions are particularly dangerous, because only radar and the sound of tornados can be warnings to people. However, most of the tornadoes arise in the late afternoon with good lighting conditions. Night tornadoes can be well lit by frequent lightning.
There are evidence from radar readings, but also from the observation that most tornados have a calm, clean eye, in which the pressure is very low, analogously, as happens in the eye of a tropical cyclone. It’s calm inside, it’s light and it’s dark, and the only source of light for those you’ve seen in the middle of a tornado can be lightning.
The name Tornado comes from the Spanish language from the word „tronada” meaning storm.
How do you detect a tornado? Tornado radar
Along with the development of computer systems, numerical weather models began to appear which made it possible to forecast meteorological mesoscale phenomena. The introduction of the Doppler radar for meteorology allowed not only to measure the intensity of rainfall, but also to detect the air circulation that occurs before and during the occurrence of a tornado.
In the US, storm forecasts are made by the Storm Prediction Center based in Oklahoma City. The center issues forecasts every several hours and describes the mesoscopic meteorological situation, among others using numerical models. These forecasts are used for warnings issued by the local offices of the US National Weather Service. Real-time observations consist of collecting data from satellite observations, weather stations, meteorological balloons, aircraft, remote sensing, observation of electrical discharges and radars. Predictions from Storm Prediction Ceneter and other information are used by the so-called „Storm hunters” and storm observers. In the US, warnings about tornadoes are issued 15-30 minutes before they appear.
Tornado natural disaster
Due to the changing climate, this phenomenon is becoming more and more common in climatic zones where there have never been any hurricanes, for example in Western and Central Europe. Originally, this name meant a tropical cyclone formed in certain regions of the Indian Ocean, but now the orcish is also called Atlantic hurricanes reaching Europe.
Although warnings of strong storms and tornadoes in the USA are reported by the local branches of the National Weather Service, a role is played by storm observers in the field dealing with detecting and reporting dangerous weather phenomena – hail, strong winds and tornadoes. In the 1970s, the US increased the focus on training storm observers. Candidates were selected from volunteers. This program has been called „Skywarn”. Observers’ task is to track dangerous atmospheric phenomena and inform local weather centers about them. This allows for quick issuing of warnings. There are around 280,000 trained storm observers in the US. In Canada, an organization of observers was created, the storm called „Canwarn”. In Europe, in many countries, observer networks are organized under the common name Skywarn Europe.
Storm observers are needed to visually determine the presence of tornadoes. The latest radar systems do not detect the presence of tornadoes, only signs indicating the possibility of its appearance (although US meteorologists are working on new algorithms detecting tornadoes). Only the observer can tell if the threat is close (eg when a condensation hopper has appeared). The role of observers is particularly large in areas remote from Doppler radar, where the measurements and results are less accurate (due to the height of the radar beam). In addition, not all weather processes leading to the creation of tornadoes are captured by the radar. Storm observers are trained to detect potentially dangerous situations. They learn to distinguish ordinary storms from storm supercells, and to see signals indicating the rapid appearance of tornadoes in a supercell.