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Cold drop

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The gota cold is a weather event. The term arose in Germany to refer to an episode of dire rains and vigorous winds, remaining established in popular culture. When it occurs, the population is afraid of considering it the harbinger of some catastrophe. However, not everything that is thought of the cold drop is true. Starting with the fact that its structure is not small as the term drop suggests.

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What is cold drop?

The cold drop is an isolated depression at high atmospheric levels formed by very cold air. It is a meteorological phenomenon that occurs every year. It causes a series of unfavorable climatic circumstances observed mainly in the Iberian Peninsula on its Mediterranean side. It is associated with heavy rains, thunderstorms, and other high-risk events.

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  • Definition
  • Cold drop characteristics
  • Source
  • Cold drop formation
  • Where it is produced
  • When it occurs
  • How long does it last
  • Effects edit
  • How to deal with the cold drop
  • Featured examples

Definition

It is a stream of cold air that emerges from a larger one located at a considerable height. When going down, it runs into warm air, causing meteorological effects of significant magnitude such as torrential downpours and storms that cause serious physical and material damage .

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The technical name of the phenomenon is High Level Isolated Depression (DANA). In addition to explaining in a simple way what this atmospheric disturbance is about, with this name, probably, it was also intended to honor the meteorologist Francisco García Dana.

He was one of the editors of the report on the storm that occurred in the Spanish Levante in October 1982, which caused the death of 38 people. It was mentioned that one of the causes of the situation was a cold drop. Since then it is believed that every similar disaster is caused by this phenomenon, which is not true.

Cold drop characteristics

This cold air mass that causes dreaded effects has the following characteristics:

  • It causes intense and torrential rainfall.
  • It occurs during the beginning of autumn.
  • It comes from Europe , it occurs on the Mediterranean coast.
  • It depends on the sea for its energy.
  • Its growth is accelerated.
  • It can reach up to 10 km in height.
  • The wind exceeds 140 km / h.
  • It spreads from top to bottom, but may remain stationary for a few days or regress.
  • It can be more than 2,000 kilometers in diameter.
  • It lacks a front line that separates it from the contiguous masses.
  • They have a particular life cycle.
  • It categorically affects the weather, which cannot be confused with the weather.

Source

The origin of the term according to the meteorological studies carried out, was in the German school, in the year 1886 when this phenomenon was named. The word kaltlufttropfen was used , whose meaning resembles a drop of cold air. Since then, and despite the appearance of the scientific word DANA, it is still popularly called in Spain and Germany, calling it a cold drop. 

Regarding the origin of the phenomenon as such, Palmén and Newton (1969) explained that the well-known rectilinear polar jet is accentuated and undulated, forging an isolation from the general circulation. They distance themselves from their natural places, closing in on themselves, originating the cold drop.

Cold drop formation

After better supported investigations, it was determined that the cold drop is formed at high altitudes. It begins when a mass of icy air that is generally directed from west to east changes its direction. This causes it to break, releasing a cold stream that collides with another of warm air when descending.

The impact occurs in the middle of the troposphere and the stratosphere giving rise to the cold drop whose consequences are winds, hail, torrential rains, electrical storms. It happens because the high temperature of the water, which evaporates with force, increases the capacity to cause precipitation.

Where it is produced

The region recognized worldwide as the center where this phenomenon occurs is the Mediterranean side of the Iberian Peninsula . It is here where the polar air collides with the hot and humid wind of the area.

However, there are other parts of Spain and South America such as Argentina , Chile , Colombia where this disturbance is also formed. The phenomenon occurs in the upper layers of the atmosphere .

When it occurs

Usually, when autumn arrives, the cold drop occurs . Possibly because at this time of year the air from the summer heat is still hovering in the coastal areas.

However, in any season it can occur, like the end of winter, in spring. At this time the effects are not usually so drastic and for this reason, erroneously, it is believed that they only occur in the autumn season.

How long does it last

It is not possible to specify exactly how long the phenomenon lasts, the time ranges from a few hours to several days. It ends when the stream that makes it up joins other jet streams. It can also merge with masses of warm air disappearing. When they stop for a certain time they cause a lot of concern.

The effects generally do not exceed a week. While they are present, the competent bodies are in charge of supplying the information to the public so that they can make the corresponding provisions.

Effects edit

These precipitations generate devastating effects like great floods. If the colliding air masses have very different temperatures, the consequences are greater.

The area where they feel most intensely is the Spanish Mediterranean side. There are numerous and successive storms with strong winds causing flooding and erosion.

It may happen that some cold drops or DANAs do not produce heavy rains or catastrophes. They are not enough to create a favorable context at low levels, nor do they generate effectively unfavorable and dangerous time.

Only in the right circumstances is it a mechanism to detonate it, although not the only one. It can also rain heavily in an alarming way due to different phenomena.

It should be noted that a direct relationship between cold drops and climatic variation has not been determined What is certain is the negative repercussions of its effects on agriculture . Many crops are lost generating losses to producers. In the same way, some storms bring down infrastructure and force the suspension of electricity service in cities.

How to deal with the cold drop

It is very important to know how to behave when faced with this phenomenon. Our security depends a lot on the attitude we assume.

  • It is necessary to know the location of the highest places of the place where we are in case a flood occurs to go towards them. If you need to move to another place, drive along the main roads away from walls, ravines and bridges.
  • We must condition the house by eliminating objects that may hinder free movement. Check the condition of the ceilings, cracks, drains and others. Have flashlights, portable lamps. Provide yourself with food, drinking water, blankets, a first aid kit.
  • You have to stay informed through the media to find out about weather forecasts.
  • Something fundamental, stay calm, be cautious, avoid risky and unnecessary actions.

Featured examples

Over time , cold drops have been produced, which are very notable for their dire consequences.

In Spain

  • October of Great flood of Valencia. Floods with many human and material losses.
  • September 1989.
  • September 1997. Alicante and the south of the province of Valencia.
  • October Marina Alta
  • October 2018. Province of Malaga,
  • September 2019. Valencian Community, Region of Murcia, Albacete and Almería. Considered the worst cold drop in 140 years that caused an unprecedented storm. The amount of water dropped in less than 24 hours exceeded 400 liters per square meter. There was enormous material damage. The agencies declared a red alert for  extreme risk.

In Southamerica

April 2013. Central Argentina

April 2014. Pacific Ocean, off the south-central coasts of Chile.

As particular data, it is highlighted that the record of maximum precipitation in 24 hours in Spain, 817 mm, is due to a cold drop. It was formed on November 3, 1987, in Oliva, Valencia.

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