Jökull - 01.01.2001, Blaðsíða 66

Þorvaldur Þórðarson and Stephen Self
Gunnlaugsson et al., 1984). However, we appear to
be less attentive to the effects that the eruption had
in other countries, perhaps due to the overwhelming
impact the events had in Iceland.
The extraordinary state of the atmosphere over
Europe in summer of 1783 was caused by persis-
tent haze (or “dry fog”) that was manifested by dim
sun, and blood–red sunrises and sunsets. These long–
lasting atmospheric perturbations were the conse-
quence of sulfuric aerosol plumes from the Laki erup-
tion in Iceland. These occurrences caused great pub-
lic concern at the time and generated wide–ranging
interest among scholars and commoners alike. Con-
sequently, contemporary records provide us with a
wealth of information on the occurrence of the Laki
haze in Europe (e.g. Steinþórsson, 1992; Grattan and
Charman, 1994; Grattan and Brayshay, 1995; Grattan,
1998; Thordarson, 1995; Stothers, 1996; Demarée
et al., 1998). Besides their obvious historic signifi-
cance, these records are of great scientific value be-
cause they provide us with an invaluable insight into
the immediate effects of the Laki haze on the contem-
porary communities. Such information is extremely
useful for predicting the potential environmental and
economic impact of future Laki–like eruptions. It is
not, however, the purpose of this report to give a com-
prehensive overview of the effects of the Laki haze
in Europe, but merely to present one of the most re-
markable contemporary reports on the subject. Here
we are referring to the attached essay written by Pro-
fessor van Swinden, most likely in 1784, where he
presents a vivid narrative of the appearance and ef-
fects of the Laki haze. Not only is it a revealing ac-
count of the magnitude and immediate consequences
of the Laki haze. It also raises concerns about how
our present day environment, which already is under
extreme stress from human pollution, will cope with
another event of similar magnitude.
The Meteorological Society of Mannheim pub-
lished the essay in 1785 as part of its annual report
for the year 1783. The original text is in Latin ex-
cept for a quotation taken from a letter written by Rev-
erend Meuran, which is in French. A shorter version
of the same essay was also published in Memoires de
l’Académie Royale du Sciences Années 1784–1785
under the title “Observations sur quelques particu-
larites meteorologiques de l’année 1783.” Professor
van Swinden refers to the haze as “nebula”, which
in translation can be taken to indicate a cloud, fog,
smoke, mist or haze. Although each of these terms
may be equally applied, we have chosen to use the
term “haze” for historical reasons. It appears to be
the most adequate translation of the Icelandic word
“móða”; a term commonly used in Icelandic chron-
icles in describing the sulfuric aerosol plumes pro-
duced by the Laki eruption.
In the first part of the essay, van Swinden reports
on his personal observations regarding the nature, ap-
pearance and effects of the Laki haze that were made
at Franeker in Holland where he resided at the time.
This is followed by a comprehensive synopsis of stud-
ies made by the botanist Dr. Brugmannus on the ef-
fects of the haze on the fauna in and around Gronin-
gen. In the latter half of the essay, van Swinden
presents a compendium on observations made on the
appearance and impact of the Laki haze elsewhere
in Europe, including a two–minded discussion on the
possible origin of the haze. Among the physical char-
acteristics of the haze that often are mentioned in the
contemporary chronicles is its dryness. Hygrometer
readings are often cited, although without giving any
specific numbers, to support the statement. In his es-
say van Swinden gives daily readings on the humidity
of the atmosphere from 18 to 30 June, thus confirming
the true nature of these observations (see his Table 1).
It is for this very reason, the haze was often referred
to in the European chronicles as the “dry fog”, simply
because it did not produce the moisture and dewdrops
that accompany “normal fog”.
Before delving into van Swinden’s essay it is per-
tinent to present a brief synopsis of the events around
the time when he and others in Europe witnessed
this extraordinary atmospheric phenomenon. Euro-
pean chronicles are a rich source on the occurrence of
the Laki haze and collectively the information gives
a comprehensive picture of the early development of
the haze over mainland Europe. Outside Iceland, the
Laki haze first appeared in the Faeroe Islands, west-
ern Norway, and northern Scotland around 10 June
(Fiacco et al., 1994; Thordarson, 1995). In western
66 JÖKULL No. 50