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Ines GRIGORESCU and Carmen-Sofia DRAGOT

Institute of Geography, Romanian Academy, Bucharest, ROMANIA


By its position within the Romanian Plain (southern part of Romania) both the capital
city Bucharest and its metropolitan area are exposed to several climatic hazards/risks
with major impact on the environment. The article emphases in detail the occurrence
and the amplitude of the hazard/risk phenomena of the cold semester (cold waves,
blizzard, snow layer, frost and hoarfrost, glazed frost etc.) and warm semester (heat
waves, rainfall, hail storms, strong winds, fog and acid rain etc.) within Bucharest
Metropolitan Area.
The authors used and processed the annual and monthly mean climatic values within
the meteorological stations from the studied area between the years 1961-2005 in
order to identify the main hazards/risks with direct impact on the environment quality
reflected on the recorded damages which have affected the settlements (roads,
houses, agricultural land etc.) and people. At the same time, on the basis of this
survey we were able to realize two climatic hazard/risk maps for each semester (cold
and warm).
The paper also analyses the synoptic conditions which have been generated the
main climatic sequences within the studied area, considered as case studies: the
heat waves of the summers of 2005 and 2007 and the amount of precipitation fallen
in September 2005 as well as their environmental impact.

Key words: climatic hazard/risk phenomena, environmental impact, Bucharest

Metropolitan Area, Romania.

Bucharest Metropolitan Area is situated in a temperate-continental area, which

is specific to the South-East of Romanian Plain, characterized by a continentalization
tendency, from the West to the East, as a result of the climatic influences of transition
in the West and excessive in the East.
The climate of the metropolitan area, which is determined by natural factors
specific to the form of relief it is related to, is completed by the multitude of the local
anthropic factors specific to the regions which enclose by the urban and rural areas.
The most important factors are:
the presence of a haze screen which often floats above the city and which
modifies the radiation regime and the condensation conditions of the water
the specific features of the surface subjacent to the formed areas predominant in
roofs (concrete, metal, tiles, wood, etc.) and pavements made of diathermic
materials with reduced heat capacity that accumulate heat during the day and
release it during the night;
the alternation of street network with green spaces of different sizes, as well as
aquatic surfaces (rivers, lakes, irrigation channels etc.);

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drainage of meteoric waters and industrial waters, through the sewage, which
reduces local evaporation and thus the heat consumption;
the existence of a very rough micro-relief, made up by the network of streets and
markets, parks, courts and buildings of different heights and orientations, which
modifies the speed and direction of the wind under the conditions of a turbulent
air mixture;
emanation in the atmosphere of the heat resulted from the fuel combustions in
industry, transportation, house heating etc.
All these factors, which have a quasi-permanent influence, are modifying the
regime of different climatic elements transmitting them to the metropolitan
environment along with the extension of the urbanization process.
Climatic risks/hazards. Due to its location and specific particularities,
Bucharest Metropolitan Area is exposed to climatic risks of major impact upon the
environment presenting a higher vulnerability to thermic, pluvial and to the mixed
The genetic conditions necessary to the production of thermic risks are mainly
caused by the atmosphere general circulation, solar radiation and by the active
subjacent surface.
During cold season, these risks are favored by the advections of cold and dry
air belonging to the Grnland, Scandinavian and East-European Anticyclones, which
generate high decrease in temperature. Depending on their frequency and intensity,
the result is cold waves with different lasting periods, and when they are produced at
the beginning of fall or at the end of spring, their effects are even more disastrous.
During the warm season of the year, the advections of marine tropical warm air,
subsequently continentalized, or the continental tropical air generated by the
continental anticyclones developed in the North of Africa, in the South-East of
Europe, in the South-West of Asia etc., determine massive warming and periods of
dryness, the longer the period, the higher their frequency and intensity.
Pluvial risks are generated by the activity of ocean cyclones, which are
developed by the Mediterranean cyclones with normal or retrogressive evolution as
well as by the cut-off cyclonic formations. These risks are likely to take place the
whole year.
Mixed risks are determined by the combined action of one or more climatic
elements under favorable synoptic circumstances and influenced by the
characteristics of the active subjacent surface.
Depending on the production moment, the main thermic, pluvial and mixed
phenomena of risks may be divided into: cold season phenomena of climatic risk and
warm season phenomena of climatic risk. Among these phenomena, the ones with a
major impact on the environment in Bucharest Metropolitan Area are the following:
Cold season phenomena of climatic risk, is represented by the thermic
minus tolerances to the normal status, caused by: the position of the baric centers
compared to the area of interest, the frequency and intensity of the cooling process
and shift speed of the air mass types. These genetic conditions are
increased/decreased by the characteristics of the subjacent surface. The main cold
season climatic risks existing in Bucharest Metropolitan area are the following:
x Polar or arctic cold waves;
x Heat waves during the winter, which cause floodings;
x Blizzard;
x Snow cover;
x Frost and rime;

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x Glazed frost;
x Icing on the aerial conductors etc.
Because of the developed technical-urban infrastructure in the city areas the
effects of these climatic risks are much mitigated.
The air masses direction of motion from the position of baric centers, which are
constant during cold season, as well as the frequency and intensity of some massive
cooling processes of the frosty and dry air waves lead to the occurrence of cold
waves. The estimation of their intensity (Bogdan, Niculescu, 1999) is calculated
depending on:
 the average monthly air temperatures ( -10 0C);
 the minimum air temperature ( -30 0C).
Usually, these cold waves are caused by non-periodical disturbances favored by
their casual occurrence, by the different intensity of the cooling processes and by the
period of manifestation. These thermic singularities become more obvious when the
absolute minimum temperatures are registered during different periods of time and
on surfaces more or less extended (Fig. 1).

Figure 1. Territorial distribution of the yearly absolute minimum temperatures

(Source: ANM)

Bucharest Metropolitan Area is exclusively included in the temperature range of

30... -35 0C generating a major climatic risk, with a negative impact on the
environment and on the human body (table 1).

Table no. 1. The absolute minimum temperatures recorded on the meteorological stations in
Bucharest Metropolitan Area
Meteorological station Absolute minimum temperature (0C) Date
Baneasa Bucharest -32,2 25.01.1942
Filaret Bucharest -30,0 25.01.1942
Afumati Bucharest -30,2 06.02.1954
Budesti -27,4 06.02.1954
Fundulea -26,5 14.02.1985
Oltenita -25,0 31.01.1987
Source: National Meteorology Administration database

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Blizzard represents a climatic risk of whose genesis is complemented by two
elements: wind speed and the thickness of the snow cover. When the speed of the
wind exceeds 15 m/s, the blizzards become violent, and when the speed of the wind
is associated with thickness of the snow cover that exceeds 25-50 cm, it causes
great damages and environmental disequilibria. The Center, the West and the East
of the Metropolitan Area of Bucharest City are vulnerable to blizzard, having a yearly
maximum frequency of 4 to 9 days, while in the North and in the South this climatic
risk is of 2 to 3 days, indicating an average vulnerability (Romania. Environment and
Electricity Transmission Grid. Geographical Atlas, 2002).
The transport infrastructure suffering the most because of the blizzard are the
ones oriented perpendicularly to the direction of the crivetz: Bucharest Giurgiu;
Bucharest Lehliu Constanta; Bucharest Ploiesti; Bucharest Alexandria and
Bucharest Buzau Suceava. We also have to mention the national roads
accompanying the arteries, but the blizzard remains a singular hazardous
meteorological phenomenon of whose effects are dictated by the quality of the
technical-urban infrastructure.
Snow cover is considered a hazardous winter meteorological phenomenon and
it is present in the Metropolitan Area of Bucharest City almost every year. The first
snow is usually produced at the end of November and the last one during the third
decade of March. Although the possible snow interval (between the earliest and the
latest day of manifestation of the phenomenon) is of approximately 100 days; the
yearly average snow days is only 53 in Bucharest-Filaret, 54 in Bucharest-Afumai and
46 in Bucharest-Baneasa.
The average decade values of the snow cover thickness varies around 10 cm
in Bucharest-Baneasa, 8 cm in Bucharest-Afumai and 12-13 cm in Bucharest-Filaret
meteorological stations. The urban areas register higher values, visibly influenced by
the urban-technical development and more decreased values in open filed because of
the snowdrifts, blizzard to the soil and in altitude. The absolute thickness of the snow
cover reaches 120-175 cm in the center of the Metropolitan Area of Bucharest during
the exceptional years, while the snow cover in the rest of the area decreases under
120 cm. Under the action of wind, especially the crivetz, the snow cover varies and the
snow is blown and withered.
The atmospheric calm or the wind with a speed under 2 m/s, as well as the
particularities of the active surface, generates important snow beddings. In return, the
wind with speed over 15 m/s, affects the stable snow layer generating snowdrifts on
all arteries located perpendicularly to the crivetz direction, especially on national
roads which start circularly from the city of Bucharest, and particularly along the
roads accompanied by skirts, forest plantations, forests etc.
In case of total or partial absence of snow covers, the soil-freezing phenomenon
is likely to appear, which causes important damages to the autumn crops and to
vegetation in general.
The freeze and hoar are hazardous meteorological phenomena which occur
during transition seasons, conditioned by the shift of the air minimum temperature on
the soil bellow the level of 0q C. These processes become phenomena with climatic
risk under two circumstances: if they occur much sooner or much later than the
average date of the first, respectively the last frost and in the situation of extremely
frosty winters, in the absence of snow cover or if it is blown away by the wind.
Almost the entire part of the area under study shows a great vulnerability to
frost (165 days/year) under the conditions of average temperatures in January,
between -2 and -3 oC, and the rest of the territory corresponding to Danube riversides

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and terraces are characterized by an average vulnerability (140 days/year) under the
conditions of some average temperatures for the month of January between -10 and
-2 0C.
High vulnerability to hoar (over 70 days/year) occurs in the central part of the
area under study, while in the rest of the metropolitan area the vulnerability to this
meteorological phenomenon is medium (50-70 days/year) (fig. 2).
Glazed frost is a meteorological phenomenon which consist in a thin layer
deposit of dense ice, mat or transparent, on the ground and objects, especially on the
side exposed to the wind, as a result of the water drops become frozen in contact on
a very cold surface. Glazed frost occurs at temperatures between 00 and 30C and it
is one of the most hazardous phenomena, having a negative impact upon all means
of transportation (road, air, cable).

Table no. 2 The average monthly and yearly number of glazed frost days (1961-2000)
Months Yearly
Meteorological station
Bucharest-Baneasa 1.2 0.6 0.3 - - - - - - 0.1 0.5 1.3
Source: National Meteorology Administration database

Generally, the most of the days with glazed frost are registered in plain areas
(between 15-20), while in the Metropolitan Area of Bucharest City the maximum
frequency is recorded during the months of December and January (tab. 2). In the
last years, as result of warmer winters, with positive temperatures for long periods of
time, the number of glazed frost days decreased even in the months with maximum
manifestation of the phenomenon.
Because it has the greatest density (0,40-0,95 g/cm3), glazed frost may cause
additional weight of the conductors, generating cable, relay, etc. tightening or even
Ice deposits on aerial conductors is a result of overcooled water freezing
(under the form of fog, foggy air, drizzle, rain), through the sublimation process and
through the adherence and freezing of snowflakes or of rain and snow. Depending on
the way of formation, ice deposits may result from glazed frost, hard or soft rime, rain
and snow, and freezing snow. The deposits may be simple (as a result of one
phenomenon) or compound (formed as a result of two or more simple deposits). The
specific parameters for these deposits are: large and small diameters, weight, type of
deposit, density and duration of deposits (tab. 3). Icing on aerial conductors modifies
the electricity supply conditions, generating disturbances in regular functioning
(Corona effect), causing wire tightening, vibration and even breakage under windy
weather. Regarding plain areas, the periods with the most frequent icing
phenomenon are at the end of autumn and beginning of spring.

Table no. 3 Maximum icing values and their characteristics

Maximum Density Maximum
Meteorological Type of Number of
weight duration of a
station deposit cases
(g\mg) D d g/cm case (ore)
Bucharest- Hard
32 14 14 0,24 1 51-100
Baneasa rime
Source: National Meteorology Administration database

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The most powerful phenomena in terms of climatic risk characteristic to the
cold semester of the year that have the biggest impact on the environment and on
the state of health of the population in the metropolitan area of Bucharest Municipal
town are: the blizzard, the frost and the white frost. At the scale of Romanian territory
certain areas have been identified with a low or high degree of vulnerability to the
mentioned above three weather phenomena that are the grounds on which critical
environmental areas have been reginalized from a climatic point of view in such a
time of the year (fig. 2)

Figure 2. Climatic risks/hazards within the warm semester of the year in

Bucharest Metropolitan Area

Climatic risk phenomena within the warm semester of the year are
influenced by the fact that the multiannual medium degree is highly overrun with
pozitive degrees, which are brought about by the general movement of the
atmosphere in correlation with solar radiation and with the nature of the subadjacent
surface. These types of climatic risk include:
- heat waves and pozitive thermic singularities;
- heavy rainfall;
- hail storms,
- thunderstorms,
- fog and acid deposits;
- manifestations of wind at a speed of 15m/s.
Heat waves and pozitive thermis singularities are generated by the
adventions of warm, topical air, and the criteria after which they are classified entail
(Bogdan, Niculescu, 1999):

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- the monthly medium temperatures of the hottest months (Jully, August) 35
- highest daily temperatures that exceed 35 C (extremely hot days)
- lowest nocturnal temperatures 20 C (tropical nights)
Regarding the impact that highest temperatures have on the human body, the
exceeding of the 35C thermic threshold is acutely felt and it has a negative effect on
human confort as well as on the normal development of the phenofazes of different
type of vegetation. Taking into consideration the fact that the 35 C temperature is
measured inside meteorological shelters, 10-15C can be added at the soil level,
which renders the thermic doisconfort even more acute. Absolute maximal values of
the air temperature in the area opf interest have exceeded 40C, reaching even 44C
(tab. 4) and having a major impact on the environment and on the general state of
health of the population, pointing a maximum degree of vulnerability to this thermic

Table no. 4
Absolute maximal temperature on values classes within Buharest Metropolitan Area
Value clases
0 0 43.0
40.0 40.9 C 41.0 41.9 C 42.0 42.9 0C 44 0C
43.9 0C
Bucharest Bucharest Valea Argovei
Bucharest Afumati
Afumati Baneasa - (Argova Valley)
41.1/5.VII.2000 42.2/5.VII.2000 44.0/10.VIII.1951
Fundulea Bucharest Filaret
Bneasa - -
41.3/16.08.1963 42.4/5.VII.2000
Budesti Fundulea
Filaret - -
41.4/16.VIII.1963 42.4/5.VII.2000
Bucharest Filaret Bucharest Filaret Oltenita
- -
40.8/7.VIII.1896 41.1/20.VIII.1945 42.7/5.VII.2000
Baneasa - - -
Gurbanesti Budesti
- - -
40.5/3.VII.1938 41.5/20.VIII.1945
Source: National Meteorology Administration database

A particular situation is the massive warming in the Summer of 2000 when

the intensity of the heat coincided with the year of maximum salar activity, just like in
the year 1946, only more intense.
The warming process began on the 2nd of Jully 2000 when the islandic
depression located in the West of the UK up to the nordic seas came into contact
with the Greenland Anticyclone, over the Atlantic Ocean towards Northern Africa. In
such a synoptic context the swift advection of the warm air over South-Western
Romania has favourised a South-Westward circulation in the inferior troposphere (fig.
3). The peak of the heat was in the interval 4-5th of Jully and it affected the Southern
half of Romania when the temperature and moisture index exceeded 80 units which
led to a highly elevated thermic risk.

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Figure 3. Baric configuration in Europe on Jully 5th 2000

On the 5th of Jully 2000, at all the meteorological stations within the Bucharest
Metropolitan Area absolute maximum temperatures exceeded 41 C (tab. 5).
Afterwards, in several consecutive sequences spreading over August as well, tropical
heat waves came one after another and were produced in the same synoptic context,
completing the massive heating situation. These temperatures along with minimum
precipitations resulted in droughty weather made even worse by extreme heat. This
situation was characteristic for the Summer of 2000.

Table no. 5 Absolute maximum temperatures of over 40C recorded in the Bucharest
Metropolitan Area in Jully 2000
Absolute Maximum
Meteorological Station Date
Temperatures (0 C)
Bucharest Afumati 41.1 5. VII
Bucharest Baneasa 42.2 5. VII
Bucharest Filaret 42.4 5. VII
Fundulea 42.4 5. VII
Oltenita 42.7 5. VII
Source: National Meteorology Administration database
Heat waves have a great impact on plants in general and especially on crops,
leading to physiological and phenological changes (the drying of leaves and plants),
and on the human body it leads to an encrease in the risk of getting ill and even to
the death of people exposed. Thus, following the heat wave in the Summer of 2000,
the Romanian Government has issued the 99/2000 Emergency Order, which was
published in the 304 Official Monitory of 04.07.2000, regarding protection measures
for the population in the case of extreme climatic phenomena.
Heavy rainfall. Through their characteristic parametres (intensity, length,
quantity), heavy rains are dependant on altitude, relief formes, solar radiation and on
the role that is played by the orographic damn in connection to the moist air
advections. The highly active dynamics of the moist tropical air or that of the polar
maritime air on Romanian territory, as well as the different levels of warming of the
earths surface determine, during summertime, the fall of heavy rains, represents a
climatic risk for the environment because of the flooding it produces.
As to the lowlands (Bucharest Metropolitan Area is located in the lowlands),
floodings are conditioned by a certain quantity of water coming from precipitations
(Milea et al., 1972):

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- in the case of dry soil a 50 l/sqm quantity of water is needed within a 24 hour
- for moist or soaked soil a 15-30 l/sqm quantity of water is needed within a 24
hour period.
Given the context, the heavy rainfall of September 2005 have a special
significance within the Bucharest Metropolitan Area, in terms of the environmental
impact. The 2005 warm semester was a period of thermic extremes, of especially
unstable atmospheric elements and of unususaly intense phenomena which are
linked to them. In terms of rainfall, this period of time was an exceptional situation for
the South of the country, and especially for Bucharest Metropolitan Area.
During this month, an Azoric air mass had spread over western and central
Europe, the baric configuration being the one that determined the contact between
polar cold air and moist masses of air from the Mediterranean Sea where an intense
cyclogenesis took place. At high altitudes, above the Mediterranean, between the
13th and the 23rd of September a cyclonic nucleus was isolated, which determined
unusual precipitations in the South-East of the Continent.

Figure 4. The baric configuration in Europe for the 22nd of September 2005

Given the sinoptic context, the full monthly amount of precipitations in the warm
semester of the year 2005, as well as those that fell within a 24 hour period, were
completely exceptional, enhancing more than one time the aspect that it was a
historical record for the entire period of time when rainfall measurements took place
in Romania.
Since the beginning of that month, periods of time with heavy rains on vast
areas could be identified throughout the country, only hours apart. We have singled
out those that took place in the Southern part of the country (Grigorescu, Dragota,
- 1-2 September Central and Eastern Muntenia, Banat and Oltenia;
- 13-14 September in Northern Oltenia and in Central and Northern Muntenia;
- 14-15 September in Banat, Oltenia, Central and Western Muntenia;
- 18-19 September in the North-West of Oltenia;
- 20-21 September in Central Muntenia, North-Eastern Muntenia and South-
Eastern Dobrogea;
- 21-23 September in the Southern half of Romania and especially in South-
Eastern Dobrogea.

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Figure. 5 The display of precipitations in September 2005

Water quantities accumulated in September 2005 have exceeded 100 mm in

vast areas in the southern half of the country (except Northern Baragan and Central
and Northern Dobrogea). Thus positive recordings are registered in regards to the
monthly average spanning over several years and are comprised in the interval of
45-80 mm in weather stations within the analysed area. In Central Muntenia and
South-East Dobrogea quantities of over 200 mm were registered. These
precipitations have affected, in that particular month, especially the Bucharest
Metropolitan Area (fig. 5)
Maximum amounts fallen in a 24 hour period of time are an indicator of the
heavy rain character of atmospheric precipitations and have developped in
September 2005 extra-ordinary values that exceeded absolute maximum amounts of
precipitations previously registered which in coparison with the entire month and with
the entire year (tab. 6)

Table no. 6 Maximum amounts of precipitations (in mm) fallen in a 24 hour period within the
Bucharest Metropolitan Area.
Maximum amounts
Maximum (September)
Meteorological maximum
Average Absolute maximum
station amounts (until
(September) amounts 2005
(until 2005)
107,0 94,5 152,3
BucharestAfumai 20,8
20.VIII.1949 11/2003 20/2005
Bucharest 107,7 94,0 126,4
Bneasa 15.VII.1954 11/2003 20/2005
136,6 100,3 161,4
Bucharest Filaret 19,9
7.VI.1910 11/2003 20/2005
103,2 24,8 106,4
Fundulea 19,6
22.VII.1959 22/1998 20/2005
102,8 86,1
Oltenita 32,6 -
12.VII.2005 4/1999
Source: National Meteorology Administration database

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Exceeding precipitations that have resulted from man-engineered floodings
affect crops, economical infrastructure (roads, bridges, railroads, electrical energy
transport networks, sewage pipes and water and gas pipes), houses, and it projected
itself both directly and indirectly into peoples lives.
The main effects of precipitations fallen in September 2005 in Bucharest
Metropolitan Area resulted in the flooding of aproximately 2,500 houses and
households in Ilfov County alone and over 190 people were evacuated. The most
troubled cities were Pantelimon, Domnesti and Buftea.

Figures 6 and 7 Broken damn on Lake Buftea (September 2005)

On the 22nd of September, Lake Buftea broke through the damn and the water
kept flowing towards Mogosoaia village as a result of the fact that the waterflow rose
from 3m3/s to 20m3/s (fig. 6 and 7)
On Lake Mogosoaia peers made out of sand bags were erected in order to stop
the waters moving forward. In Comana, Giurgiu County, the earth flooring that most
poor families in the village had turned into genuine swamps (fig. 8) and the local train
station was flooded (fig. 9).

Figures 8 and 9 Flood effects in Comana Commune, Giurgiu County

The amounts of water that supply the lakes around Bucharest have grown
about ten times within a 24 hour period reaching record waterflows, and in Domnesti
town Ciorogarla river burst its banks flooding many a house.
Hail is a climatic risk phenomenon which takes place in the warm semester of
the year. It has major repecussions on the environment. Usually, hail il associated
with heavy raining and lightning. In the northern sector of Bucharest a rather large

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island-like area can be identified as having great vulnerability to such a climatic risk
(the maximum amount of days with hail per year is 5-10). The rest of the area has a
fairly moderate vulnerability (4-5 days per year) and the South-East has a low degree
of vulnerability (under 4 days per year) (Romania. The environment and the
Transportation Electrical Network, Geographical Atlas, 2002)
Thunderstorms fall into the category of electrometeors and are defined by
sudden electrical discharges in the atmosphere. They appear as an intense and
short-lived ray of light (lightning) accompanied by a loud thud (thunder).
Thunderstorms are often associated with convection clouds (Cumulonimbus) and are
usually accompanied by heavy precipitaions.

Table no. 7 Medium and maximum amount of days with thunderstorms per month and
per year (1961-2000)
Meteorological Month
med. 0.2 0.2 0.3 2.1 6.2 9.2 7.8 5.8 2.3 0.8 0.2 0.1 35.2
Bucharest- 3 2 3 6 13 16 16 10 5 4 1 2 54
Bneasa 1970 1975
yr 1962 1967 2000 1975 1970 1972 1966 1967 1980 1966 1975
1971 1969
Source: National Meteorology Administration database

On a yearly basis, in Romania the average number of days ranges between 30-
35 in plain regions, and 35.2 days at the Bucharest-Baneasa weather station. All
through the year, thunderstorms take place mainly in the warm semester. The
maximum amount is reached in Jully when the heaviest amount of precipitations also
fal. (tab. 7).
Fog and acid deposits are a heavy source of atmosphere pollution. Due to to
the mecanic effect (fog) and the chemical one (acid deposits) it has a great negative
impact on the environment.
Fog is basically atmospheric suspension in the form of microscopical drops
which cause a diminished visibility in distances of under one kilometre. Fog, in
whichever form it may come, has a negative impact on transportation activities (road
transport, water transport, air transport, sewage transport) and on the general state
of health of the population.

Table no. 8 The monthly and annual number of foggy days (1961-2000)
Meteorological Month Annualy
Bucharest- 52.2
10.9 8.0 3.8 1.3 0.9 0.5 0.2 0.4 1.0 4.3 9.5 11.4
Source: National Meteorology Administration database

The highes monthly frequence of fog in a one year period of time can be
registered during Winter (December- January), and the lowes in Sumer months
(Jully- August).
When fog is associated with various polluting substances, its effect on the
environment increases alongside these substancess level of concentration, and the
intensity and the length of the parametres characteristic to this weather phenomenon
increase or diminish the amounts of polluting substances that exist in the given miro-
climatic space. The fact that Romania is exposed to this kind of climatic risk involved
six levels of vulnerability depending on the number of days with such a phenomenon
per year (Romania. The Environment and The Electric Transportation Network.

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Geographical Atlas, 2002) Bucharest Metropolitan Area is set entirely in a high level
of vulnerability lasting between 36 to 50 days per year.
Precipitations associated with polluting substances increase the fogs negative
impact on the environment as well. In some polluted areas like some different regions
within Bucharest Metropolitan Area, 5% of polluting substances that can be found in
the atmosphere can adhere to precipitations that fall on the earth (wash-out). In the
case when precipitation come from a dirty cloud, highly polluted (rain-out), the
polluting substances reach the earth alongside the precipitations at very long
distances from their source.
Acid precipitations or acid rain that have a pH value lower than 5.6 involve the
process of dry or moist depositing on the earth of acid material coming from the
atmosphere. Without rainfall or some other form of precipitations, atmospheric
polluting substances are shifted from the atmosphere by the gravitationnal force that
attacts them to the earths surface and through direct contact with the soil, the
vegetation and the buldings. The rate of dry sedimentation of polluting substances
varies between 0.1 and 1.0 cm/sec (tab. 9)

Table no. 9 Dry sedimentation speed

Poluani Viteza (cm/s)
SO2 0,1 1,0
NO2 0,2 0,5
Sulfai 0,1
Azotai 1,0
after Frca, Croitoru, 2003
Dry deposits can have a very important contribution to increasing acidity levels
in both dry and moist deposits. Thay bear the name of acid deposits (Farcas,
Croitoru, 2003) which take place along with fog risk and within the topoclimatic
conditions of the area known as the Island of Hat of the Bucharest Metropolitan Area.
After 1989, as the industrial activities of chemical plants decreased, the number of
areas with vulnerability to such a climatic risk has also diminished, maintaining the
consequences of productive years. Due to the fact that road traffic has increased, the
mobile pollution sources have also risen in numbers which, associated with risk
weather phenomena (fog, acid deposits, dense and heavy fog) have amajor impact
on the environment and on the general state of health of the population.
Wind at speeds of over 15m/sec are generated by thermo-baric contrasts
between the different areas characterised by earth horisontal gradients with high
values, which can happen at any time during the year. In the cold semester these
winds are associated with snowfall. Yet in the warm semester they become climatic
risks associated especially with extreme heat periods or with the beginning of heavy
rains season. The mecanic effect generated by such winds is twice reinforced by by
the large amounts of polluting substances spead into the atmosphere, which
generates an increased vulnerability of the environment to such a rosk phenomenon.
Taking into consideration the annual frequency of winds with speeds exceeding
15m/sec., one notices that, generally, Bucharest Metropolitan Area has a low
vulnerability state (16-20 cases per year). In the South of the MetropolitanArea, along
the Danube river plain the degree of vulnerability is average (61-70 cases per year)
and the Center and East of Mostistea Plain has an elevated degree of vulnerability
(71-100 cases per year).

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Figure 10. Climatic risks/hazards in the warm semester of the year in
Bucharest Metropolitan Area

Among the climatic risk phenomena characteristic to the warm semester of the
year as to Bucharest Metropolitan Area, those that have a major impact on the
environment and on the general state of health of the population were singled out:
heat waves and positive thermic singularities along with hail (fig 10). Areas with
high, average or low vulnerability to hail were identified and areas with high and
average vulnerability to positive temperatures were discovered so as to establish with
critical environment from a climatic point of view within the warm semester of the
Both in Romania, as a country, and within Bucharest Metropolitan Area the
rapid shift of certain extreme weather phenomena take place: heavy rain, tornados,
sudden temperature rise of over 30-35C and cold periods of time which subject the
human body to adaptation shocks.
Within Bucharest Metropolitan Area, among the climatic risk phenomena, the
ones involving thermic and rain risk stand out. As one of these risks, heavy rainfall
has the greatest impact on the environment through the extent of the damage it
inflicts. Extreme heat and heat waves also represent a major impact due to the fact
that human lives are lost.
Because they endure and because they are intense, these climatic risk
phenomena within Bucharest Metropolitan Area are either triggering factors of factors
that support other categories of natural risks: geomorphological, hydrological, soil
related and even ecological ones.

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Selected bibliography

Blteanu D., Grigorescu Ines, (2005), The Metropolitan Area of Bucharest

Municipality. Present-day features related to some environmental issues within the
international context, Romanian Review of Regional Studies, Nr. 1, pg. 35-46, Presa
Universitar Clujean
Blteanu D., Grigorescu Ines, (2006), The impact of Changing land Use upon the
Environment in the Metropolitan Area of Bucharest. Preliminary Considerations,
Romanian Review of Regional Studies Journal of the Centre for Regional
Geography, Volume II, Nr. 1, pg. 35-44, Presa Universitar Clujean, Cluj-Napoca
Bogdan Octavia, Niculescu Elena, (1999), Riscurile climatice din Romania, Editura
Liga Internationala, Bucuresti
Dragot, Carmen-Sofia, Blteanu, D. (1998), Impactul precipitaiilor atmosferice
excedentare i a vntului asupra utilizrii terenurilor n Romnia, Analele Universitii
tefan Cel Mare, Suceava, Seciunea Geografie-Geologie, anul VII/1998, p.201-
Dragot, Carmen-Sofia (2006), Precipitaiile excedentare n Romnia, Editura
Academiei Romne.
Grigorescu Ines, (2005), Indici de evaluare a calitii mediului n Aria Metropolitan
a Municipiului Bucureti, Revista Geografic, T. XI,
Grigorescu Ines, (2006), Some environmental issues related to rural development
during the transition period in Bucharest metropolitan area. Romania; Procedeengs
of the Rural areas in the new development conditions Symposium, Ohrid,
Macedonia, Tome 2,
Grigorescu Ines, Dragot Carmen Sofia, (2006), Fenomene de risc termic i
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Transversal, Trgovite
Marinica I., (2006), Fenomene climatice de risc in Oltenia, Editura Autograf MIM,
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Geographical Atlas, Editura Academiei Romane, Bucuresti
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