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Electric current
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A simple electric circuit, where current is represented by the letter i. The relationship between the voltage (V), resistance (R), and current (I) is V=IR; this is known as Ohm's law.
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An electric current is a flow of electric charge.[1]:2 In electric circuits this charge is often carried by moving electrons in a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in an ionised gas (plasma).[2]
The SI unit for measuring an electric current is the ampere, which is the flow of electric charge across a surface at the rate of one coulomb per second. Electric current is measured using a device called an ammeter.[3]
Electric currents cause Joule heating, which creates light in incandescent light bulbs. They also create magnetic fields, which are used in motors, inductors and generators.
The moving charged particles in an electric current are called charge carriers. In metals, one or more electrons from each atom are loosely bound to the atom, and can move freely about within the metal. These conduction electrons are the charge carriers in metal conductors.
Contents
[hide]
1 Symbol
2 Conventions
2.1 Reference direction
3 Ohm's law
4 Alternating and direct current
5 Occurrences
6 Current measurement
7 Resistive heating
8 Electromagnetism
8.1 Electromagnet
8.2 Radio waves
9 Conduction mechanisms in various media
9.1 Metals
9.2 Electrolytes
9.3 Gases and plasmas
9.4 Vacuum
9.5 Superconductivity
9.6 Semiconductor
10 Current density and Ohm's law
11 Drift speed
12 See also
13 References
Symbol
The conventional symbol for current is I, which originates from the French phrase intensité de courant, (current intensity).[4][5] Current intensity is often referred to simply as current.[6] The I symbol was used by André-Marie Ampère, after whom the unit of electric current is named, in formulating Ampère's force law (1820).[7] The notation travelled from France to Great Britain, where it became standard, although at least one journal did not change from using C to I until 1896.[8]
Conventions
The electrons, the charge carriers in an electrical circuit, flow in the opposite direction of the conventional electric current.
The symbol for a battery in a circuit diagram.
In a conductive material, the moving charged particles that constitute the electric current are called charge carriers. In metals, which make up the wires and other conductors in most electrical circuits, the positively charged atomic nuclei are held in a fixed position, and the negatively charged electrons are free to move, carrying their charge from one place to another. In other materials, notably the semiconductors, the charge carriers can be positive or negative, depending on the dopant used. Positive and negative charge carriers may even be present at the same time, as happens in an electrolyte in an electrochemical cell.
A flow of positive charges gives the same electric current, and has the same effect in a circuit, as an equal flow of negative charges in the opposite direction. Since current can be the flow of either positive or negative charges, or both, a convention is needed for the direction of current that is independent of the type of charge carriers. The direction of conventional current is arbitrarily defined as the same direction as positive charges flow.
Since electrons, the charge carriers in metal wires and most other parts of electric circuits, have a negative charge, as a consequence, they flow in the opposite direction of conventional current flow in an electrical circuit.
Reference direction
Since the current in a wire or component can flow in either direction, when a variable I is defined to represent that current, the direction representing positive current must be specified, usually by an arrow on the circuit schematic diagram. This is called the reference direction of current I. If the current flows in the opposite direction, the variable I has a negative value.
When analyzing electrical circuits, the actual direction of current through a specific circuit element is usually unknown. Consequently, the reference directions of currents are often assigned arbitrarily. When the circuit is solved, a negative value for the variable means that the actual direction of current through that circuit element is opposite that of the chosen reference direction. In electronic circuits, the reference current directions are often chosen so that all currents are toward ground. This often corresponds to the actual current direction, because in many circuits the power supply voltage is positive with respect to ground.
Ohm's law
Main article: Ohm's law
Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. Introducing the constant of proportionality, the resistance,[9] one arrives at the usual mathematical equation that describes this relationship:[10]
I = V R {\displaystyle I={\frac {V}{R}}}
where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms. More specifically, Ohm's law states that the R in this relation is constant, independent of the current.[11]
Alternating and direct current
See also: War of Currents
In alternating current (AC) systems, the movement of electric charge periodically reverses direction. AC is the form of electric power most commonly delivered to businesses and residences. The usual waveform of an AC power circuit is a sine wave. Certain applications use different waveforms, such as triangular or square waves. Audio and radio signals carried on electrical wires are also examples of alternating current. An important goal in these applications is recovery of information encoded (or modulated) onto the AC signal.
In contrast, direct current (DC) is the unidirectional flow of electric charge, or a system in which the movement of electric charge is in one direction only. Direct current is produced by sources such as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. An old name for direct current was galvanic current.[12]
Occurrences
Natural observable examples of electrical current include lightning, static electric discharge, and the solar wind, the source of the polar auroras.
Man-made occurrences of electric current include the flow of conduction electrons in metal wires such as the overhead power lines that deliver electrical energy across long distances and the smaller wires within electrical and electronic equipment. Eddy currents are electric currents that occur in conductors exposed to changing magnetic fields. Similarly, electric currents occur, particularly in the surface, of conductors exposed to electromagnetic waves. When oscillating electric currents flow at the correct voltages within radio antennas, radio waves are generated.
In electronics, other forms of electric current include the flow of electrons through resistors or through the vacuum in a vacuum tube, the flow of ions inside a battery or a neuron, and the flow of holes within a semiconductor.
Current measurement
Current can be measured using an ammeter.
At the circuit level, various techniques are used to measure current:
Shunt resistors[13]
Hall effect current sensor transducers
Transformers (however DC cannot be measured)
Magnetoresistive field sensors[14]
Resistive heating
Main article: Joule heating
Joule heating, also known as ohmic heating and resistive heating, is the process by which the passage of an electric current through a conductor produces heat. It was first studied by James Prescott Joule in 1841. Joule immersed a length of wire in a fixed mass of water and measured the temperature rise due to a known current through the wire for a 30 minute period. By varying the current and the length of the wire he deduced that the heat produced was proportional to the square of the current multiplied by the electrical resistance of the wire.
Q ∝ I 2 R {\displaystyle Q\propto I^{2}R}
This relationship is known as Joule's First Law. The SI unit of energy was subsequently named the joule and given the symbol J. The commonly known unit of power, the watt, is equivalent to one joule per second.
Electromagnetism
Electromagnet
Main article: Electromagnet
In an electromagnet a coil, of a large number of circular turns of insulated wire, wrapped on a cylindrical core, behaves like a magnet when an electric current flows through it. When the current is switched off, the coil loses its magnetism immediately. [15][16]
According to Ampère's law, an electric current produces a magnetic field.
Electric current produces a magnetic field. The magnetic field can be visualized as a pattern of circular field lines surrounding the wire that persists as long as there is current.
Magnetism can also produce electric currents. When a changing magnetic field is applied to a conductor, an Electromotive force (EMF) is produced, and when there is a suitable path, this causes current.
Electric current can be directly measured with a galvanometer, but this method involves breaking the electrical circuit, which is sometimes inconvenient. Current can also be measured without breaking the circuit by detecting the magnetic field associated with the current. Devices used for this include Hall effect sensors, current clamps, current transformers, and Rogowski coils.
Radio waves
Main article: Radio waves
When an electric current flows in a suitably shaped conductor at radio frequencies radio waves can be generated. These travel at the speed of light and can cause electric currents in distant conductors.
Conduction mechanisms in various media
Main articles: Electrical conductivity and Charge transport mechanisms
In metallic solids, electric charge flows by means of electrons, from lower to higher electrical potential. In other media, any stream of charged objects (ions, for example) may constitute an electric current. To provide a definition of current independent of the type of charge carriers, conventional current is defined as moving in the same direction as the positive charge flow. So, in metals where the charge carriers (electrons) are negative, conventional current is in the opposite direction as the electrons. In conductors where the charge carriers are positive, conventional current is in the same direction as the charge carriers.
In a vacuum, a beam of ions or electrons may be formed. In other conductive materials, the electric current is due to the flow of both positively and negatively charged particles at the same time. In still others, the current is entirely due to positive charge flow. For example, the electric currents in electrolytes are flows of positively and negatively charged ions. In a common lead-acid electrochemical cell, electric currents are composed of positive hydrogen ions (protons) flowing in one direction, and negative sulfate ions flowing in the other. Electric currents in sparks or plasma are flows of electrons as well as positive and negative ions. In ice and in certain solid electrolytes, the electric current is entirely composed of flowing ions.
Metals
In a metal, some of the outer electrons in each atom are not bound to the individual atom as they are in insulating materials, but are free to move within the metal lattice. These conduction electrons can serve as charge carriers, carrying a current. Metals are particularly conductive because there are a large number of these free electrons, typically one per atom in the lattice. With no external electric field applied, these electrons move about randomly due to thermal energy but, on average, there is zero net current within the metal. At room temperature, the average speed of these random motions is 106 metres per second.[17] Given a surface through which a metal wire passes, electrons move in both directions across the surface at an equal rate. As George Gamow wrote in his popular science book, One, Two, Three...Infinity (1947), "The metallic substances differ from all other materials by the fact that the outer shells of their atoms are bound rather loosely, and often let one of their electrons go free. Thus the interior of a metal is filled up with a large number of unattached electrons that travel aimlessly around like a crowd of displaced persons. When a metal wire is subjected to electric force applied on its opposite ends, these free electrons rush in the direction of the force, thus forming what we call an electric current."
When a metal wire is connected across the two terminals of a DC voltage source such as a battery, the source places an electric field across the conductor. The moment contact is made, the free electrons of the conductor are forced to drift toward the positive terminal under the influence of this field. The free electrons are therefore the charge carrier in a typical solid conductor.
For a steady flow of charge through a surface, the current I (in amperes) can be calculated with the following equation:
I = Q t , {\displaystyle I={Q \over t}\,,}
where Q is the electric charge transferred through the surface over a time t. If Q and t are measured in coulombs and seconds respectively, I is in amperes.
More generally, electric current can be represented as the rate at which charge flows through a given surface as:
I = d Q d t . {\displaystyle I={\frac {\mathrm {d} Q}{\mathrm {d} t}}\,.}
Electrolytes
Main article: Conductivity (electrolytic)
Electric currents in electrolytes are flows of electrically charged particles (ions). For example, if an electric field is placed across a solution of Na+ and Cl− (and conditions are right) the sodium ions move towards the negative electrode (cathode), while the chloride ions move towards the positive electrode (anode). Reactions take place at both electrode surfaces, absorbing each ion.
Water-ice and certain solid electrolytes called proton conductors contain positive hydrogen ions ("protons") that are mobile. In these materials, electric currents are composed of moving protons, as opposed to the moving electrons in metals.
In certain electrolyte mixtures, brightly coloured ions are the moving electric charges. The slow progress of the colour makes the current visible.[18]
Gases and plasmas
In air and other ordinary gases below the breakdown field, the dominant source of electrical conduction is via relatively few mobile ions produced by radioactive gases, ultraviolet light, or cosmic rays. Since the electrical conductivity is low, gases are dielectrics or insulators. However, once the applied electric field approaches the breakdown value, free electrons become sufficiently accelerated by the electric field to create additional free electrons by colliding, and ionizing, neutral gas atoms or molecules in a process called avalanche breakdown. The breakdown process forms a plasma that contains enough mobile electrons and positive ions to make it an electrical conductor. In the process, it forms a light emitting conductive path, such as a spark, arc or lightning.
Plasma is the state of matter where some of the electrons in a gas are stripped or "ionized" from their molecules or atoms. A plasma can be formed by high temperature, or by application of a high electric or alternating magnetic field as noted above. Due to their lower mass, the electrons in a plasma accelerate more quickly in response to an electric field than the heavier positive ions, and hence carry the bulk of the current. The free ions recombine to create new chemical compounds (for example, breaking atmospheric oxygen into single oxygen [O2 → 2O], which then recombine creating ozone [O3]).[19]
Vacuum
Since a "perfect vacuum" contains no charged particles, it normally behaves as a perfect insulator. However, metal electrode surfaces can cause a region of the vacuum to become conductive by injecting free electrons or ions through either field electron emission or thermionic emission. Thermionic emission occurs when the thermal energy exceeds the metal's work function, while field electron emission occurs when the electric field at the surface of the metal is high enough to cause tunneling, which results in the ejection of free electrons from the metal into the vacuum. Externally heated electrodes are often used to generate an electron cloud as in the filament or indirectly heated cathode of vacuum tubes. Cold electrodes can also spontaneously produce electron clouds via thermionic emission when small incandescent regions (called cathode spots or anode spots) are formed. These are incandescent regions of the electrode surface that are created by a localized high current. These regions may be initiated by field electron emission, but are then sustained by localized thermionic emission once a vacuum arc forms. These small electron-emitting regions can form quite rapidly, even explosively, on a metal surface subjected to a high electrical field. Vacuum tubes and sprytrons are some of the electronic switching and amplifying devices based on vacuum conductivity.
Superconductivity
Main article: Superconductivity
Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics.
Semiconductor
Main article: Semiconductor
In a semiconductor it is sometimes useful to think of the current as due to the flow of positive "holes" (the mobile positive charge carriers that are places where the semiconductor crystal is missing a valence electron). This is the case in a p-type semiconductor. A semiconductor has electrical conductivity intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 10−2 to 104 siemens per centimeter (S⋅cm−1).
In the classic crystalline semiconductors, electrons can have energies only within certain bands (i.e. ranges of levels of energy). Energetically, these bands are located between the energy of the ground state, the state in which electrons are tightly bound to the atomic nuclei of the material, and the free electron energy, the latter describing the energy required for an electron to escape entirely from the material. The energy bands each correspond to a large number of discrete quantum states of the electrons, and most of the states with low energy (closer to the nucleus) are occupied, up to a particular band called the valence band. Semiconductors and insulators are distinguished from metals because the valence band in any given metal is nearly filled with electrons under usual operating conditions, while very few (semiconductor) or virtually none (insulator) of them are available in the conduction band, the band immediately above the valence band.
The ease of exciting electrons in the semiconductor from the valence band to the conduction band depends on the band gap between the bands. The size of this energy band gap serves as an arbitrary dividing line (roughly 4 eV) between semiconductors and insulators.
With covalent bonds, an electron moves by hopping to a neighboring bond. The Pauli exclusion principle requires that the electron be lifted into the higher anti-bonding state of that bond. For delocalized states, for example in one dimension – that is in a nanowire, for every energy there is a state with electrons flowing in one direction and another state with the electrons flowing in the other. For a net current to flow, more states for one direction than for the other direction must be occupied. For this to occur, energy is required, as in the semiconductor the next higher states lie above the band gap. Often this is stated as: full bands do not contribute to the electrical conductivity. However, as a semiconductor's temperature rises above absolute zero, there is more energy in the semiconductor to spend on lattice vibration and on exciting electrons into the conduction band. The current-carrying electrons in the conduction band are known as free electrons, though they are often simply called electrons if that is clear in context.
Current density and Ohm's law
Main article: Current density
Current density is a measure of the density of an electric current. It is defined as a vector whose magnitude is the electric current per cross-sectional area. In SI units, the current density is measured in amperes per square metre.
I = ∫ J → ⋅ d A → {\displaystyle I=\int {\vec {J}}\cdot d{\vec {A}}}
where I {\displaystyle I} is current in the conductor, J → {\displaystyle {\vec {J}}} is the current density, and d A → {\displaystyle d{\vec {A}}} is the differential cross-sectional area vector.
The current density (current per unit area) J → {\displaystyle {\vec {J}}} in materials with finite resistance is directly proportional to the electric field E → {\displaystyle {\vec {E}}} in the medium. The proportionality constant is called the conductivity σ {\displaystyle \sigma } of the material, whose value depends on the material concerned and, in general, is dependent on the temperature of the material:
J → = σ E → {\displaystyle {\vec {J}}=\sigma {\vec {E}}\,}
The reciprocal of the conductivity σ {\displaystyle \sigma } of the material is called the resistivity ρ {\displaystyle \rho } of the material and the above equation, when written in terms of resistivity becomes:
J → = E → ρ {\displaystyle {\vec {J}}={\frac {\vec {E}}{\rho }}} or
E → = ρ J → {\displaystyle {\vec {E}}=\rho {\vec {J}}}
Conduction in semiconductor devices may occur by a combination of drift and diffusion, which is proportional to diffusion constant D {\displaystyle D} and charge density α q {\displaystyle \alpha _{q}} . The current density is then:
J = σ E + D q ∇ n , {\displaystyle J=\sigma E+Dq\nabla n,}
with q {\displaystyle q} being the elementary charge and n {\displaystyle n} the electron density. The carriers move in the direction of decreasing concentration, so for electrons a positive current results for a positive density gradient. If the carriers are holes, replace electron density n {\displaystyle n} by the negative of the hole density p {\displaystyle p} .
In linear anisotropic materials, σ, ρ and D are tensors.
In linear materials such as metals, and under low frequencies, the current density across the conductor surface is uniform. In such conditions, Ohm's law states that the current is directly proportional to the potential difference between two ends (across) of that metal (ideal) resistor (or other ohmic device):
I = V R , {\displaystyle I={V \over R}\,,}
where I {\displaystyle I} is the current, measured in amperes; V {\displaystyle V} is the potential difference, measured in volts; and R {\displaystyle R} is the resistance, measured in ohms. For alternating currents, especially at higher frequencies, skin effect causes the current to spread unevenly across the conductor cross-section, with higher density near the surface, thus increasing the apparent resistance.
Drift speed
The mobile charged particles within a conductor move constantly in random directions, like the particles of a gas. (More accurately, a Fermi gas.) To create a net flow of charge, the particles must also move together with an average drift rate. Electrons are the charge carriers in most metals and they follow an erratic path, bouncing from atom to atom, but generally drifting in the opposite direction of the electric field. The speed they drift at can be calculated from the equation:
I = n A v Q , {\displaystyle I=nAvQ\,,}
where
I {\displaystyle I} is the electric current
n {\displaystyle n} is number of charged particles per unit volume (or charge carrier density)
A {\displaystyle A} is the cross-sectional area of the conductor
v {\displaystyle v} is the drift velocity, and
Q {\displaystyle Q} is the charge on each particle.
Typically, electric charges in solids flow slowly. For example, in a copper wire of cross-section 0.5 mm2, carrying a current of 5 A, the drift velocity of the electrons is on the order of a millimetre per second. To take a different example, in the near-vacuum inside a cathode ray tube, the electrons travel in near-straight lines at about a tenth of the speed of light.
Any accelerating electric charge, and therefore any changing electric current, gives rise to an electromagnetic wave that propagates at very high speed outside the surface of the conductor. This speed is usually a significant fraction of the speed of light, as can be deduced from Maxwell's Equations, and is therefore many times faster than the drift velocity of the electrons. For example, in AC power lines, the waves of electromagnetic energy propagate through the space between the wires, moving from a source to a distant load, even though the electrons in the wires only move back and forth over a tiny distance.
The ratio of the speed of the electromagnetic wave to the speed of light in free space is called the velocity factor, and depends on the electromagnetic properties of the conductor and the insulating materials surrounding it, and on their shape and size.
The magnitudes (not the natures) of these three velocities can be illustrated by an analogy with the three similar velocities associated with gases. (See also hydraulic analogy.)
The low drift velocity of charge carriers is analogous to air motion; in other words, winds.
The high speed of electromagnetic waves is roughly analogous to the speed of sound in a gas (sound waves move through air much faster than large-scale motions such as convection)
The random motion of charges is analogous to heat – the thermal velocity of randomly vibrating gas particles.
See also
Electronics portal
Current 3-vector
Direct current
Electric shock
Electrical measurements
History of electrical engineering
Hydraulic analogy
International System of Quantities
SI electromagnetism units
Single-phase electric power
Two-phase electric power
Three-phase electric power
References
Jump up ^ Horowitz, Paul; Hill, Winfield (2015). The art of electronics (3rd ed.). Cambridge University Press. ISBN 978-0-521-80926-9.
Jump up ^ Anthony C. Fischer-Cripps (2004). The electronics companion. CRC Press. p. 13. ISBN 978-0-7503-1012-3.
Jump up ^ Lakatos, John; Oenoki, Keiji; Judez, Hector; Oenoki, Kazushi; Hyun Kyu Cho (March 1998). "Learn Physics Today!". Lima, Peru: Colegio Dr. Franklin D. Roosevelt. Archived from the original on 2009-02-27. Retrieved 2009-03-10.
Jump up ^ T. L. Lowe, John Rounce, Calculations for A-level Physics, p. 2, Nelson Thornes, 2002 ISBN 0-7487-6748-7.
Jump up ^ Howard M. Berlin, Frank C. Getz, Principles of Electronic Instrumentation and Measurement, p. 37, Merrill Pub. Co., 1988 ISBN 0-675-20449-6.
Jump up ^ K. S. Suresh Kumar, Electric Circuit Analysis, Pearson Education India, 2013, ISBN 9332514100, section 1.2.3 "'Current intensity' is usually referred to as 'current' itself."
Jump up ^ A-M Ampère, Recueil d'Observations Électro-dynamiques, p. 56, Paris: Chez Crochard Libraire 1822 (in French).
Jump up ^ Electric Power, vol. 6, p. 411, 1894.
Jump up ^ Consoliver, Earl L.; Mitchell, Grover I. (1920). Automotive ignition systems. McGraw-Hill. p. 4.
Jump up ^ Robert A. Millikan and E. S. Bishop (1917). Elements of Electricity. American Technical Society. p. 54.
Jump up ^ Oliver Heaviside (1894). Electrical papers. 1. Macmillan and Co. p. 283. ISBN 0-8218-2840-1.
Jump up ^ Andrew J. Robinson; Lynn Snyder-Mackler (2007). Clinical Electrophysiology: Electrotherapy and Electrophysiologic Testing (3rd ed.). Lippincott Williams & Wilkins. p. 10. ISBN 978-0-7817-4484-3.
Jump up ^ What is a Current Sensor and How is it Used?. Focus.ti.com. Retrieved on 2011-12-22.
Jump up ^ Andreas P. Friedrich, Helmuth Lemme The Universal Current Sensor. Sensorsmag.com (2000-05-01). Retrieved on 2011-12-22.
Jump up ^ We And Our World. D.A.V. College Managing Committee.
Jump up ^ From the book/ We And Our World
Jump up ^ "The Mechanism Of Conduction In Metals", Think Quest.
Jump up ^ Rudolf Holze, Experimental Electrochemistry: A Laboratory Textbook, page 44, John Wiley & Sons, 2009 ISBN 3527310983.
Jump up ^ "Lab Note #106 Environmental Impact of Arc Suppression". Arc Suppression Technologies. April 2011. Retrieved March 15, 2012.
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text:
2018 Great Britain and Ireland cold wave
From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
2018 Great Britain and Ireland cold wave
Satellite view showing Europe, including Great Britain and Ireland partially covered in snow under the influence of the strong cold wave on 27 February 2018
Formed
24 February 2018
Dissipated
4 March 2018
Total fatalities
16 (preliminary) [1]
Areas affected
Great Britain and Ireland
Beginning on 24 February 2018, the United Kingdom and Ireland were affected by a cold wave, dubbed the Beast from the East by the media, which brought widespread unusually low temperatures and heavy snowfall to large areas. The cold wave combined with Storm Emma, part of the 2017–18 UK and Ireland windstorm season, which made landfall in southwest England and southern Ireland on 2 March.
In contrast to usual winter storms, Emma was not formed as a normal low pressure area along with the jetstream; the initial event was an arctic outbreak due to a disordered polar vortex into Central Europe, transporting not only cold air from Siberia to Europe, but on the way to the British Islands according to the lake effect sent a lot of snow into areas of Great Britain and Ireland.
This weather situation repeated itself on the weekend of 17 and 18 March, but was less severe than on the previous occasion due to the onset of spring. This briefer cold snap was given the name "Mini Beast from the East".
Contents
[hide]
1 Beast from the East
2 Storm Emma
3 Mini Beast from the East
4 References
Beast from the East[edit]
See also: 2017–18 European windstorm season § Beast from the East
The cold spell nicknamed the Beast from the East was caused by a large arctic airmass with anticyclonic structure, stretching from the Russian Far East to the British Isles covering large parts of Asia and almost all of Europe. The anticyclone, centered over Scandinavia,[2] is the dominant high pressure area in the weather system and represents its European part. North Asia was covered by other anticyclones that belong to that giant arctic airmass. The anticyclone brought cold easterly winds into Europe and the British Isles leading to snowfall and sub-zero temperatures as result of freezing air from Siberia.[3][4] Ireland was predicted to experience its worst winter for at least 30 years.[5][6] In the United Kingdom the Met Office issued a red snow warning, meaning a potential risk to life.[7]
The anticyclone, nicknamed 'Hartmut' was such an intense high pressure system that it evolved into an anticyclonic storm. A gust of 187 km/h was registered in the Øvre Dividal National Park in Norway, relatively near to the anticyclonic centre.[8] Other hurricane-force gusts delivered by Hartmut were registered across Europe, particularly over Scandinavia and the British Isles. Such hurricane-force anticyclonic storms are not extremely rare, but occur less often than cyclonic storms of similar intensity.
16 weather-related deaths include that of a seven-year-old girl in Looe, Cornwall Thursday 1 March, when she was hit by a car that slid on ice into a bungalow. On Wednesday 28 February, Stephen Cavanagh, 60, died after trying to save his dog from a lake in Welling, South East London. Also on Wednesday, a 46-year-old man died in a crash and a 75-year-old woman was found dead underneath her car in Farsley. A carer from Glasgow died on her way to work and a 52-year-old homeless man was found dead freezing inside his tent. On Tuesday, 27 February, four people died in two separate weather related crashes. A 20-year-old also died after slipping and falling whilst crossing a bridge in Haddington, East Lothian. This followed the death of a man trying to help another driver in the snowy conditions in Bergh Apton, Norfolk who suffered a heart attack. A 70-year-old also died after being rescued from icy cliffs in Torquay.
"Beast from the East" cold wave fatalities
Country
Fatalities
Notes
Poland 27[9]
[10][11][12][13]
UK 17[14][11][15][16]
[17][18][17][11]
Due to mixed effects of Storm Emma and the cold wave.[18][17]
Slovakia 7[11][19]
France 7[9][10][11][12][13][20]
Czech Republic 6[21]
Romania 6[22][23][9][19][10][22][22][12][22][12][13]
Lithuania 5[10]
Spain 3[10]
Serbia 3[19][21][10][24]
Slovenia 3[19][21][10][24]
Italy 3[10]
Sweden 1[25][8]
The Netherlands 1[10]
Germany 1[10]
Denmark 1[21][10]
Bosnia-Herzegovina 1[19][24][26]
Croatia 1[19][24]
Albania 1[19][20][27] [20]
Bulgaria 1[19]
Total
93
Storm Emma[edit]
See also: Winter Storm Emma (2018)
Storm Emma brought chaos with heavy snow and strong winds to Southern Ireland, South West England and Southern Wales on the 2–3 March 2018 with up to 50 cm of snow in some elevated areas.[28] High winds brought disruption to other parts of Great Britain and Ireland.
Mini Beast from the East[edit]
Following a brief spell of warmer weather, a fresh cold snap nicknamed the "Mini Beast from the East" was forecast to bring another covering of snow on the weekend of 17 and 18 March. However, due to the onset of spring, and a higher sun position, it was forecast that the effect would be less severe than on the previous occasion, as the ground was warmer than before so the snow would melt more quickly.[29][30]
Snow showers began to affect parts of Britain and Ireland on 17 March, with north-east England, the North Midlands, and parts of southern England experiencing the heaviest snowfall. The snow was accompanied by strong winds, forecast to be as high as 70mph, and the Met Office issued an amber weather warning effective from the afternoon of 17 March.[31] Snow showers continued to affect parts of the UK and Ireland on 18 March, with South West England the most severely affected. The adverse weather conditions forced the cancellation of some sporting events, including the Reading Half Marathon, while Ireland's rugby union team, who had won the 2018 Six Nations Championship, cancelled their homecoming "due to heavy snowfall" with no new date confirmed.[32]
References[edit]
Jump up ^ "Families told 'evacuate now' as storm brings intense flooding". 3 March 2018. Retrieved 18 March 2018.
Jump up ^ http://www.met.fu-berlin.de/de/wetter/maps/Analyse_20180228.gif
Jump up ^ Greenfield, Patrick (2018-02-26). "UK braces for 'beast from the east' as Met Office warns of snow". the Guardian. Retrieved 2018-02-27.
Jump up ^ Greenfield, Patrick; Rawlinson, Kevin (2018-02-23). "Siberian blast could make southern England colder than the Arctic". the Guardian. Retrieved 2018-02-28. ...Freezing air from Siberia...
Jump up ^ Thorne, Peter (2018-02-26). "Q&A: What is causing these severe snow warnings?". the Irish Times. Retrieved 2018-02-28. There have been many worse winters in the past, but not in the last 30 years. Met Éireann have a good compendium of historical events available at www.met.ie. ... Peter Thorne is Professor in Physical Geography (Climate Change) at NUI Maynooth and Director of the Irish Climate Analysis and Research Unit group (Icarus)
Jump up ^ LeCouer, Jack (2018-02-26). "Be Ready As Beast Set To Bite". Nova.ie. Retrieved 2018-02-28. Evelyn Cusack from Met Éireann says the winds coming from Siberia will mean it’s exceptionally cold, and said it’s been more than 30 years since we’ve seen this kind of weather: “I’m not saying that it’s going to be as bad, maybe it’ll be worst.”
Jump up ^ "UK weather: Snow causing widespread travel disruption". BBC News. BBC. 28 February 2018. Retrieved 28 February 2018.
^ Jump up to: a b "Messwerte vom 28.02.2018, 07:00 Uhr – Troms". Retrieved 2 March 2018.
^ Jump up to: a b c "Deadly storm dubbed 'Beast from the East' pounds Europe". 27 February 2018.
^ Jump up to: a b c d e f g h i j k [1][dead link]
^ Jump up to: a b c d e "AFP.com". AFP.com.
^ Jump up to: a b c d "Deadly storm dubbed 'Beast from the East' pounds Europe". 27 February 2018.
^ Jump up to: a b c "Deadly storm dubbed 'Beast from the East' pounds Europe". 27 February 2018.
Jump up ^ Duggan, Joe (2 March 2018). "Forty cars involved in huge pile-up as Brits battle home in treacherous weather".
Jump up ^ News, ABC. "ABC News". ABC News.
Jump up ^ "Ice-Proofing Pays Off as Heathrow Endures Rare London Blizzard". 1 March 2018 – via www.bloomberg.com.
^ Jump up to: a b c "Body found in canal in search for Manchester teen who vanished in cold weather". 3 March 2018.
^ Jump up to: a b Sales, Dan (2018-03-03). "UK weather sparks warnings to 'evacuate now' despite dangerous roads as Storm Emma brings deadly flooding and freezing rain". the Guardian. Retrieved 2018-03-03.
^ Jump up to: a b c d e f g h [2][dead link]
^ Jump up to: a b c http://amp.miamiherald.com/news/nation-world/article202314409.html
^ Jump up to: a b c d "The Latest: Cold weather kills mean in Slovenia, Serbia". 28 February 2018.
^ Jump up to: a b c d "Two killed as 'Beast from the East' paralyses Europe". 28 February 2018.
Jump up ^ "'Beast from the East' causes death, disruption in Europe".
^ Jump up to: a b c d "Deadly storm dubbed 'Beast from the East' pounds Europe – Today World News Online". todayworldnewsonline.com.
Jump up ^ "Record-setting cold weather continues to grip Europe". Anadolu Agency.
Jump up ^ "Deadly storm dubbed 'Beast from the East' pounds Europe – Today World News Online". todayworldnewsonline.com.
Jump up ^ http://amp.miamiherald.com/news/business/article202123994.html
Jump up ^ "Storm Emma to bring up to 50cm of snow". 2 March 2018. Retrieved 2 March 2018 – via www.bbc.co.uk.
Jump up ^ "'Mini Beast from the East' brings fresh snow warnings". BBC. 2018-03-16. Retrieved 2018-03-18.
Jump up ^ "UK weather: 'Mini Beast from the East' set to grip Britain as Met Office extends weekend snow and ice warnings". The Telegraph. 2018-03-16. Retrieved 2018-03-18.
Jump up ^ "Snow and ice sweep across parts of UK". 17 March 2018. Retrieved 18 March 2018 – via www.bbc.co.uk.
Jump up ^ "Travel warnings as snow and ice hit UK". 18 March 2018. Retrieved 18 March 2018 – via www.bbc.co.uk.
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