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TYPE
Original Research
PAGE NO.
157-174
DOI
OPEN ACCESS
SUBMITED
24 February 2025
ACCEPTED
22 March 2025
PUBLISHED
29 April 2025
VOLUME
Vol.05 Issue 04 2025
COPYRIGHT
© 2025 Original content from this work may be used under the terms
of the creative commons attributes 4.0 License.
Analysis of the Spatial and
Temporal Variability of
Thunderstorms and their
General Trend in Iraq
Asst. Lect. Zainab Kadhim Jawad Shukur
Ministry of Education Directorate of Education, Najaf Iraq
Abstract:
The thunderstorm is one of the familiar
weather phenomena all over the world. It is one of the
sudden electrical discharges accompanied by a flash of
light (lightning) and a strong sound (thunder). Since the
speed of light is much greater than the speed of sound,
the sound of thunder lags behind the sight of lightning
after approximately five seconds. The thunderstorm is
accompanied by strong wind hea, rain, honing, and
thunder. Nevertheless, the thunderclouds only form
when controlling a state of instability, a noticeable
depth of air in the atmosphere, and if the disturbed air
is moist.
The study includes three topics: the first topic
(Thunderstorms and their causes), the second topic
(the spatial and temporal variability of thunderstorms),
and the third topic (the general trend of thunderstorms
in Iraq). And the problem of the study was represented
(do thunderstorms vary spatially and temporally in
Iraq?). The hypothesis states (thunderstorms differ
spatially and temporally in Iraq). The research aims to
study the frequency of thunderstorms and the ratio of
cloud cover in the sky for the period (1980-2012) to
report the factors that determine their occurrence and
geographical distribution to determine the times when
they occur and analyze the spatial and temporal
variability of thunderstorms and their general direction
in Iraq. The research reached several results, the most
important of which are:
1. The month of April records the highest frequency of
thunderstorms at all stations except for the wet station,
records the month of October at an average of (2.3
days) due to the air turbulence and the rising air
currents responsible for the instability as well as the
increase in the condensation tendencies flying from the
atmosphere which is one of the basic conditions for the
formation of clouds Among them are the
cumulonimbus clouds which are responsible for the
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formation of rainy thunderstorms. Mosul leads the
stations of the study area in the frequency of
thunderstorms for this month at a rate of up to (4.6
days).
2. During this period, the Mosul station took the lead
in total frequency among the stations included in the
study (19.8 days) due to its geographical location in
northern Iraq and the passage of the Mediterranean
lows.
3. The general trend of the thunderstorms is towards
the increase in all the stations to reach the trend to
(0.05, 0.02, 0.03, 0.05, 0.001, 0.04, 0.003) for the
stations (Mosul, Baghdad, Al-Rutba, Karbala, Al-Hay,
Najaf, Basra) respectively.
Keywords:
Target Costing Technique, Quality Function,
Improving Product Value, Production Costs.
Introduction:
A thunderstorm is a common
atmospheric phenomenon worldwide. It is a sudden
electrical discharge accompanied by a flash of light
(lightning) and a loud sound (thunder). Since the speed
of light is much greater than the speed of sound, the
sound of thunder is delayed by approximately five
seconds after the lightning is seen.
A thunderstorm is accompanied by strong winds, heavy
rain, lightning, and thunder, evidence of the
tremendous amount of energy expended during a
severe thunderstorm. Most of this energy is derived
from the total latent heat released by the condensation
of water vapor, with some of this heat converted into
kinetic energy, which is explained by the strong winds
accompanying the storm. However, thunderclouds only
form when there is a noticeable profound atmospheric
instability, and the turbulent air is humid.
Research Problem:
(Do thunderstorms vary spatially and temporally in
Iraq?)
1- How are thunderstorms distributed spatially and
temporally in Iraq?
2- What is the general trend of thunderstorms?
Research Objective:
(Thunderstorms vary spatially and temporally in Iraq)
1- Thunderstorms are distributed spatially and
temporally in Iraq, increasing in the northern and
western parts and decreasing in the central and
southern parts. Temporally, they increase in the spring.
2- The general trend of thunderstorms in Iraq is toward
an increase.
Research Objectives:
The research aims to study the frequency of
thunderstorms and the percentage of cloud cover in
the sky (1980-2012) in different parts of the country. It
also aims to determine the factors that determine their
occurrence, their geographical distribution, and the
times of their occurrence.
Boundaries of the Study Area:
The following climatic stations represent the spatial
boundaries:
(Mosul - Baghdad - Rutba - Karbala - Al-Hayy - Najaf -
Basra).
The temporal boundaries are limited to the period
(1980-2012). Table (1) Climate stations included in the
study.
Stations
Height in
meters
Latitude
Longitude
Mobile
223
˚36 1̅9
˚43 0̅9
Baghdad
31.7
˚33 1̅8
˚44 2̅4
Anbar
630
˚33 0̅2
˚40 1̅7
Karbala
33
˚33 3̅2
˚45 4̅3
Al-Hay
17
˚32 0̅8
˚46 0̅2
Najaf
32
˚31 5̅7
˚44 1̅9
Basra
2.4
˚30 3̅1
˚47 4̅7
Source: Republic of Iraq, Ministry of Transport and Communications, General Authority for Meteorology and
Seismic Monitoring, Climate Atlas of Iraq, Baghdad.
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Figure (1)
Location of stations in the study area
Source: Republic of Iraq, Ministry of Transport and Communications, General Authority for Meteorology and
Seismic Monitoring, Iraq Climate Atlas, Baghdad, 1979.
Section One
Thunderstorms and their causes
First: Definition of thunderstorms and their results
Thunderstorms are sudden electrical discharges that
can occur in all regions of the world, including the study
area, due to their association with the visible and
audible phenomena of lightning and thunder, which are
among the primary conditions required in every storm.
Despite the small area occupied by thunderstorms,
which are formed by strong ascending air currents, they
are often accompanied by intense lightning and
thunder, high-speed winds, and very heavy rain, with
hail in most cases. Due to the varying intensity of
ascending air currents and the amount of moisture they
carry, they have been divided into rainy and non-rainy
thunderstorms. Thunderstorms are localized storms
accompanied by thunder, lightning, and heavy rain,
forming over a short period of time and preceded by
violent gusts of surface wind, although air speed is
primarily vertical.
Cumulonimbus clouds, formed by strong upward air
currents, are not responsible for all thunderstorms.
They rapidly rise upward in the form of a massive anvil,
like large towers. They also appear dark when viewed
from their base due to their great thickness. The
importance of this phenomenon lies in its role as a
major source of water vapor and energy distribution in
the atmosphere, as they absorb heat and moisture
from the layers of the atmosphere and transfer it to the
upper atmosphere, contributing to wind generation
and the consolidation of thermal energy. They are also
the basis for generating atmospheric electricity on clear
days.
Thunderstorms are also known as powerful storms
containing lightning and thunder. They are constantly
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present in the atmosphere, so aircraft encountering
thunderstorms is inevitable. Thunderstorms are a
frightening weather phenomenon for pilots and cause
significant delays to flight schedules. The pilot works
hard to avoid thunderstorms by circling them and
staying away from their locations.
Thunderstorm Formation:
For a thunderstorm to form, there must be currents
carrying water vapor from the surface, and there must
be an uplift of moist air in the atmosphere. This
uplifting mechanism includes mountain ranges, cold
fronts, depressions, and atmospheric troughs.
• Conditions for Thunderstorms:
The conditions for thunderstorm formation include:
1. The presence of moist air near the Earth's surface.
The source of the moisture may be local or external.
2. The presence of atmospheric instability, as this helps
activate updrafts.
3. The presence of a driver for updrafts, along with a
surface heating factor, such as terrain or air fronts.
4. The presence of an upper thermal inversion, which
contributes to the formation of large thunderstorms, as
heating continues in the atmospheric layer below the
thermal inversion, and the intensity of the instability
increases until cumulus clouds can penetrate the
thermal inversion layer. Therefore, small cumulus
clouds grow below the thermal inversion layer and do
not form a strong storm unless the instability intensifies
and the clouds penetrate the thermal inversion layer,
growing and rising to the tropopause.
5- Dew point temperatures rise to more than 10°C,
which activates condensation and rain formation. It has
been found that a storm is weak if the dew point
temperature is below 10°C. Second: The Life Stages of
a Thunderstorm
A thunderstorm goes through three stages, depending
on the prevailing direction and the magnitude of
vertical air movement. These stages are:
• The first stage: called the cumulus stage, typically
lasting between 10 and 15 minutes. This stage is
characterized by the presence of only ascending air
currents and the absence of descending air currents.
These ascending air currents are pushed to heights of
up to 5 kilometers, in turn leading to the formation of
the clouds responsible for the thunderstorm,
particularly the cumulonimbus type. This occurs when
a state of severe atmospheric instability prevails at a
significant depth in the atmosphere. Furthermore, the
turbulent air is associated with high humidity, as well as
the lifting force of the ascending air currents, which are
similar to the intense heating of the Earth's surface or
along the air fronts accompanying the low-pressure
system, particularly the cold ones. The temperature in
most parts of the cloud is above zero degrees Celsius,
except for some areas at the top of the cloud.
• The second stage: called the mature stage, typically
lasting between 15 and 30 minutes. It is considered one
of the most dangerous stages of a thunderstorm due to
the presence of ascending and descending air currents,
along with the electrical charges that pervade the
cloud. This stage also includes the lightning and
thunder phenomena that accompany this stage. These
air currents rise to high altitudes, possibly exceeding
the troposphere. The speed of the electrical currents
reaches 300 km/h. The temperature in most areas of
the cloud falls below zero degrees Celsius. This
indicates the presence of solid water, which may be in
the form of ice crystals, hail, or hail.
• The third stage: called the dissipating stage,
typically
lasting approximately 30 minutes. It is characterized by
the dispersal of the large cloud, with its upper part
remaining at the tip of the anvil. Downward air currents
dominate over upward air currents due to the cooling
of the ground surface caused by the cold air current,
which interrupts the upward air currents, stopping
them in the direction of the thunderstorm. Factors
responsible for the formation of thunderstorms:
1- Surface winds:
When a thunderstorm arrives, cold, descending air
currents collide with the ground and spread in all
directions, spreading at a greater speed toward the
front of the thunderstorm. Wind speeds can reach 25
m/s. These winds play a significant role in determining
whether the thunderstorm dissipates or continues as it
was.
1- Atmospheric Pressure:
When a thunderstorm forms, the atmospheric pressure
tends to decrease due to the dominance of ascending
air currents. However, its value changes as the
thunderstorm matures, i.e., when the ascending and
descending air currents become active. With each
descending current, there is a rise in pressure, and with
each ascending current, there is a decrease in pressure,
with the overall pressure remaining low as the storm
passes.
2- Temperature:
Temperature is associated with a drop during the
passage of a thunderstorm due to the cold descending
air that spreads upon impact with the ground. The
temperature drops suddenly, by approximately 10°C,
mitigating the intensity of the heat, which is then
accompanied by a rapid drop in pressure.
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3- Rainfall:
Despite the many types of clouds responsible for
forming a thunderstorm, cumulonimbus clouds are
directly responsible for the phenomenon. They are
characterized by the heavy rainfall that accompanies
them during the storm, but their short duration of
rainfall, which does not exceed 30 minutes.
4- Hail
Hail is a product of thunderstorms associated with
cumulonimbus clouds, also known as hail clouds,
because their repeated descent and ascent allow the
initial hailstones to grow and become lar
ger. • Types of
Thunderstorms
1- Rainy Thunderstorms:
These are storms accompanied by heavy rain due to the
thickness of the clouds responsible for thunderstorms,
which are linked to the type of air fronts accompanying
the frontal depression. Cold fronts play a major role in
creating instability and contribute to the formation of
the clouds responsible for thunderstorms. This is due to
the movement of cold air, which lifts warm, moist air
into the upper layers of the atmosphere. Upon reaching
the level of elevation condensation, it condenses,
forming dense Cumulonimbus clouds, which lead to
heavy rain accompanied by thunderstorms along a
narrow band of the front. The intense heating of the
Earth's surface also leads to the formation of
cumulonimbus
clouds,
which
develop
into
cumulonimbus clouds as a result of the rise of moisture-
laden air to high levels due to convection currents,
which are responsible for the formation of this type of
rain cloud. Therefore, it is clear from the above that the
main factors responsible for the rainfall accompanying
thunderstorms are the type of depression, which
comes in the order of The second, particularly during
the fall and spring seasons, is the unstable weather
associated with the Red Sea depressions and other
thermal depressions.
2- Non-rainy thunderstorms:
These are storms characterized by thunder and
lightning, but are not accompanied by rain due to the
thinness of the clouds responsible for them, resulting
from low relative humidity values. This occurs when the
air is relatively dry and stable, which in turn leads to the
formation of medium and high clouds, which are
responsible for the occurrence of non-rainy
thunderstorms.
• Thunderstorm Contents:
1-
Lightning: Thunderstorms are named so because they
are accompanied by thunder. Thunder always occurs
with lightning, as humans can see and hear. Lightning
occurs in large cumulus clouds and does not occur in
small, thin clouds. Most lightning occurs in tropical
regions where strong weather storms are frequent.
Lightning results from the separation of negative and
positive
charges
within
the
cloud
during
thunderstorms. This creates a gradient in electrical
potential. When this gradient reaches a critical value,
electrical contact occurs between the areas of negative
and positive charges, resulting in lightning. Lightning
can occur within the cloud itself, between a cloud and
another cloud, or between a cloud and the ground. The
most common type is lightning that occurs within a
cloud or between clouds and lightning. Lightning occurs
between the bottom of the cloud and the ground,
causing bodily harm. Lightning occurs in pulses that
occur in stages. The lightning bolt begins between the
bottom of the cloud and the lightning bolt, with a spark
moving rapidly from the area of negative charge
accumulation at the bottom of the cloud. Towards the
ground, it attracts the positive charges that form on
areas or objects high on the surface of the earth, so a
positively charged flash rises from the ground upwards
when the negative atmospheric charges approach the
surface of the earth, and lightning occurs.
When an electrical discharge occurs between negative
and positive charges (lightning), the air along the
lightning bolt, with a diameter of about 2 cm, heats up,
reaching temperatures exceeding 15,000 degrees
Celsius. This sudden and rapid heating results in the
sudden expansion and contraction of the air, creating
shock waves that radiate from the lightning strike area,
causing a loud sound known as thunder. Lightning can
be seen from great distances, but thunder can only be
heard at a distance of about 25 kilometers from the
lightning strike. Therefore, a person may see lightning
but not hear the thunder when the storm is far away.
• Types of Lightning:
Lightning appears during thunderstorms in various
forms, including:
1- Sheet lightning: It occurs in the form of wide,
luminous sheets. It is seen when lightning illuminates
part of the sky and clouds.
2- Heat lightning: It occurs when the cloud is far away.
Lightning is seen on the horizon, but the sound of
thunder is not heard.
3- Forked lightning: This is the most common type and
usually extends from the base of a cloud to the ground.
4- Ribbon lightning: This is in the form of lines or bands
and occurs when strong winds pull lightning along with
the wind and carry it downward at high speed.
5- Broken lightning: This occurs at short, intermittent
intervals and is often seen as a seven-pointed star.
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6- Bell lightning: This is a rare and unexpected
occurrence. It falls from the sky in the form of a small,
luminous, and hot ball, about 15 cm in diameter. Ball
lightning does not last long on the ground and
disappears within a few seconds. Ball lightning is not
well understood.
• Harmful effects of lightning:
Lightning has been documented to cause significant
damage on Earth. It can down power and
communication cables, cause forest fires, and kill or
injure large numbers of people annually. It is
responsible for the deaths of 5,000 people worldwide
annually. It is noted that lightning damages high areas
or objects, such as electricity poles, radio or television
transmission poles, and people. It kills people who are
higher than the surrounding areas, such as those riding
a horse or swimming in open water. In these cases, the
person is high up and is struck by lightning. Lightning
kills a number of people who are near or in contact with
high areas, such as people near metal fences, under tall
or isolated trees, or when using electrical appliances
such as telephones and televisions.
To
protect
yourself
from
lightning
during
thunderstorms:
1. It is preferable to stay indoors or in your car during a
strong thunderstorm, as the car is a safe place from
lightning.
2. Do not use your phone unless necessary, and do not
touch your television to change channels.
3. Stay away from open water, such as seas and lakes,
and stay away from telephone and electricity poles,
fences, metal pipes, tall or isolated trees, and avoid
using agricultural machinery and bicycles.
4- If you are outside, seek suitable shelter, avoiding high
objects and moving your div toward objects in the
area. Take shelter in a low-lying area.
• Phenomena associated with thunderstorms:
1- Lightning
2- Blizzard
3- Tornado
4- Downdrafts
5- Heavy rain
6- Lightning pellets that may be of enormous size
• The role and importance of thunderstorms:
Thunderclouds
are
important
mechanisms
in
distributing energy in the atmosphere, taking heat and
moisture from the lower layers of the atmosphere and
transferring them to the upper layers. The energy of a
thunderstorm is equivalent to 10 times the energy
generated by the nuclear bomb dropped on Hiroshima.
There are approximately 2,000 active thunderclouds on
Earth at one time, but only 1% of these clouds produce
hail the size of 3/4 inch or generate strong downdrafts.
Section Two
Spatial and Temporal Variation of Thunderstorms
First: Spatial and Temporal Variation of Thunderstorms
By observing Table (2) and Figure (2), which show the
monthly average frequency of thunderstorms with rain,
it is clear that there are variations in frequency
between stations depending on their location and the
multiple factors responsible for their formation, and for
all stations during the study period. During this period,
Mosul Station occupied the top spot in total frequency
among the stations included in the study, with a total
of (19.8 days), due to its geographical location in
northern Iraq and its position as a corridor for
Mediterranean low-pressure systems. April records the
highest frequency of thunderstorms at all stations, with
the exception of Rutba Station, which records an
average of 2.3 days in October. This is due to air
disturbance and rising air currents responsible for the
instability, as well as an increase in condensation nuclei
emanating from the atmosphere, which are a
prerequisite
for
cloud
formation,
including
cumulonimbus clouds, responsible for the formation of
rain-laden thunderstorms. Mosul tops the study area
stations in the frequency of thunderstorms for this
month, with an average of 4.6 days.
Table (2)
:
Monthly average number of thunderstorm days and annual total in the study area for the period
(1980-2012)
Stati
ons
De
ce
mb
er
2
Fe
br
ua
ry
Ma
rch
Ap
ril
Ma
y
Ju
ne
Jul
y
Au
gus
t
Se
pte
mb
er
Oc
tob
er
1
No
ve
mb
er
De
ce
mb
er
1
Ann
ual
total
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Mos
ul
1.2
1.7
2.2
4.6
3.2
0.8
0.2
0.2
0.7
2.3
1.7
1.1
19.8
Bagh
dad
0.9
1.1
1.7
2.8
2.4
0.1
0.0
0.0
0.3
2.3
2.2
1.1
14.9
Anba
r
0.4
0.6
1.2
2.
1
2.2
0.2
0.1
0.1
0.1
2.3
0.8
0.5
10.6
Karb
ala
0.7
0.7
1.6
2.5
1.3
0.2
0.0
0.0
0.1
1.7
1.3
1.1
11.1
Al-
Hayy
0.8
1.2
1.4
2.5
1.2
0.2
0.0
0.1
0.1
1.3
1.6
1.0
11.3
Naja
f
1.0
0.8
1.7
2.3
2.0
0.2
0.0
0.0
0.0
0.9
1.3
1.0
11.3
Basr
a
1.1
1.7
2.4
2.6
1.7
0.1
0.0
0.0
0.2
1.6
2.1
1.3
14.9
Source: Republic of Iraq, Ministry of Transport
and Communications, General Authority for
Meteorology and Seismic Monitoring, Climate
Department, unpublished data, 2013.
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Figure (2)
:
Monthly average number of thunderstorm days and annual total in the study area for the period
(1980-2012)
Source: Table (2)
:
Second: Geographical distribution of thunderstorms
Thunderstorms can occur anywhere on Earth, but with
varying frequencies. Thunderstorms are most common
in areas between the equatorial latitude and the
latitude, with a frequency of approximately 225
thunderstorms per year. This rate decreases to 100-180
thunderstorms per year in the highlands of North and
South America and Central Africa. The number of
thunderstorms in desert areas decreases to less than 10
storms per year, as in the Kalahari Desert in southwest
Africa.
• Spatial and temporal distribution of rainy
thunderstorms:
Thunderstorms occur either at the front or rear of a
low-pressure system, as cold fronts pass through the
low-pressure system during the winter. The
geographical distribution of the number of days with
thunderstorms in the study area reveals a clear
variation between the study stations, due to the
different topographical features and the increased
frequency of frontal depressions and their direct and
indirect effects on the frequency of thunderstorms. By
observing Table (3), which shows the monthly and
seasonal frequency of thunderstorms, it is clear that
there are variations in frequency between stations,
depending on their location and the multiple factors
responsible for their formation.
Table (3)
Monthly frequency of thunderstorms in the study area for the period (1980-2012)
Statio
ns
Septem
ber
Octo
ber
Novem
ber
Decem
ber
Janua
ry
Febru
ary
Mar
ch
Ap
ril
M
ay
Tot
al
Mosul
/
1,5
1,5
1,5
0,9
1,4
2,6
3,5
3,2
,
16
1
Baghd
ad
0,1
2,3
3,1
1,9
0,8
1,2
1,9
3,1
2,3
,
16
7
Rutba
0.3
2,8
1,5
0,7
0,5
0,6
1,3
1,5
2,4
,
11
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6
Al-
Hayy
/
0,7
1,3
1,0
0,5
0,9
1,2
3,1
0,3
9,0
Basra
0.1
2,2
1,2
2,3
1,1
1,1
1,5
3,1
1,9
,
14
5
Source: Nader Mohammed Siam, Air Masses and
Fronts, Journal of Science and Technology, Riyadh
1999, p. 7
Overall, during the study period, Baghdad station
ranked first in total seasonal occurrences among the
stations included in the study, with an average of (16.7)
storms. This is because Baghdad is considered one of
the cities with a broader local climate than other cities,
where air turbulence and rising air currents are
responsible for the instability, in addition to the
condensation nuclei emanating from its atmosphere,
which are one of the basic conditions for cloud
formation, including cumulonimbus clouds, which are
responsible for the formation of rainy thunderstorms.
Next, Mosul station came in second with an average of
(16.1)
storms.
The
increased
frequency
of
thunderstorms in the northern and central regions is
due to the increased frequency of air fronts
accompanying frontal depressions within their general
eastward movement, as well as the intense heating of
the mountain slopes facing solar radiation during the
months of March, April, and May. This causes the
formation of cumulus clouds, often followed by active
thunderstorms as a consequence of the passage of a
frontal depression. Regarding the temporal distribution
of thunderstorms, it is noted that there is a clear
concentration in the number of days during which
thunderstorms occur during certain months of the year.
Most cases of atmospheric instability occur during the
rainy season, from late autumn to late spring. Most of
these cases occur when the study area is under the
influence of cold fronts, especially if the fronts are
associated with cold upper basins. As shown in Table
(3), the spring months occupied the top spot in the total
frequency of rainy thunderstorms for all stations
included in the study. The reason for this is that the
lower layer of air adjacent to the Earth’s surfac
e is
exposed to intense heating, so convection currents
become active in the afternoon during the spring days,
accompanied by cold air masses in the upper layers of
the atmosphere, in addition to the effect of the study
area with some cold spring air fronts that are
sometimes active, so the weather becomes ready for
the occurrence of a state of instability, causing rainy
thunderstorms during this period. Autumn ranks
second in the average number of days with
thunderstorms and rain across all study stations. The
reason for the high frequency during autumn can be
attributed to the increased instability in the humid air
that prevails in the region when low-pressure systems
pass. There is a significant difference between the
temperature of the warm surface and the air adjacent
to it, on the one hand, and the cooler air above it, on
the other. This causes unusual instability that leads to
thunderstorms accompanied by rain. Despite the
activity of low-pressure systems passing through the
study area during the winter, the average number of
days with thunderstorms is lower compared to the fall
and spring seasons. This is due to the small
temperature differences between opposing air masses,
which prevents the occurrence of atmospheric
instability during which thunderst
orms form. • Spatial
and temporal distribution of non-rainy thunderstorms:
The geographical distribution of the number of days of
non-rainy
thunderstorms in the study area does not
differ from the geographical distribution of the
number of days of rainy thunderstorms, despite
variations in their total frequency among stations in
the study area. Table (4) shows that the stations
where this phenomenon occurs most frequently are
the central stations in the region.
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Table (4)
Monthly average frequency of non-rainy thunderstorms in the study area for the period (1980-2012
)
Source: Nader Muhammad Siam, Air Fronts, Journal of Science and Technology, Riyadh 1999, p. 7.
Baghdad Station ranked first in terms of total seasonal
frequency among the stations in the study area, with an
average of (5.3) storms, followed by Al-Hayy Station
with an average of (4.0) storms. Al-Rutba Station
ranked third with an average of (3.4) storms. This is due
to the arrival of dry air masses causing instability,
resulting in the formation of non-rainy thunderstorms.
Meanwhile, Mosul Station recorded an average of (3.0)
storms, followed by Basra Station with an average of
(2.6) storms.
To achieve the purpose of the temporal distribution of
the number of days with non-rainy thunderstorms, it is
necessary to analyze the reasons for the variation in
their frequency from one season to the next and from
one month to the next. Table (3) shows that the
unstable months, during which frontal depressions
recur, recorded the highest frequency of this
phenomenon due to the activity of upward convection
currents. It is noted that the spring months occupy the
forefront in this regard for all the stations included in
the study. While May ranked second after April in
frequency, March ranked third.
Referring to Table (4), it is noted that autumn maintains
a distinguished position in the total number of days
with recurring non-rainy thunderstorms. October
recorded the highest frequency of this phenomenon.
The Rutba station had the highest frequency, with an
average of 0.9 storms, due to its desert location and the
arrival of dry air masses to the region, which leads to
instability that allows for the formation of non-rainy
thunderstorms.
Meanwhile, the average number of days with recurring
non-rainy thunderstorms decreased during the winter
months for all stations included in the study due to the
recurrence of cold atmospheric highs, which lower
temperatures and create smaller temperature
differences between the ground surface temperature
and the air layer above it, reducing the occurrence of
instability. Section Three
(General Trend of Thunderstorms in Iraq)
By observing Table (5) and Figure (3), which show the
general trend of thunderstorms for the most frequent
months in the study area, it is noted that the general
trend of thunderstorms is increasing at all stations,
reaching (0.05, 0.02, 0.03, 0.05, 0.001, 0.04, 0.003) for
the stations (Mosul, Baghdad, Rutba, Karbala, Al-Hay,
Najaf, and Basra), respectively.
Table (5)
:
General Trend of Thunderstorms for the Most
Frequent Months in the Study Area for the Period
(1980-2012)
Month
General
trend
Mosul
April
0.05
Baghdad
April
0.02
Rutba
October
0.03
Karbala
April
0.05
Stations
September
October
November
December
January
February
March
April
May
Total
Mosul
0,1
0,5
0,3
0,3
0,1
/
0,3
0,9
0,5
3,0
Baghdad
0,3
0,5
0,7
0,5
/
0,3
0,6
1,1
1,3
5,3
Anbar
0,2
0,9
0,1
0,2
/
0,1
0,4
0,9
0,6
3,4
Al-Hayy
0,2
0.6
0,5
0,3
0,5
0,0
0,4
1,1
0,4
4,0
Basra
/
0.5
0,4
0,1
0.3
0,1
0,5
0,2
0,5
2,6
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Al-Hayy
April
0.001
Najaf
April
0.04
Basra
Month
0.003
Source: Researcher's work
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Figure (3)
The general trend in the number of thunderstorm days for the most frequent months in the study area for the
period (1980-2012)
Source: The researcher's work is based on the Republic of Iraq, Ministry of Transport and Communications,
General Authority for Meteorology and Seismic Monitoring, Climate Department, unpublished data, 2013
CONCLUSIONS
1- April records the highest frequency of thunderstorms
at all stations, except Rutba Station, which records an
average of 2.3 days in October. This is due to air
disturbance and rising air currents responsible for the
instability, as well as an increase in condensation nuclei
emitted from the atmosphere, which are one of the
basic conditions for cloud formation, including
cumulonimbus clouds, responsible for the formation of
rainy thunderstorms. Mosul leads the stations in the
study area in the frequency of thunderstorms for this
month, with an average of 4.6 days.
2- Mosul station ranked first in total frequency among
the stations included in the study, with a total of (19.8
days), due to its geographical location in northern Iraq
and its position as a corridor for Mediterranean low-
pressure systems.
3- The general trend of thunderstorms is increasing at
all stations, reaching (0.05, 0.02, 0.03, 0.05, 0.001, 0.04,
0.003) for the stations (Mosul, Baghdad, Rutba,
Karbala, Al-Hayy, Najaf, and Basra), respectively.
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