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<div>This study investigates the temporal variation of suspended particles with aerodynamic diameter less than or equal to 10 μm (PM<sub>10</sub>) during an eighteen years period.... more
<div>This study investigates the temporal variation of suspended particles with aerodynamic diameter less than or equal to 10 μm (PM<sub>10</sub>) during an eighteen years period. Mean daily PM<sub>10</sub> concentrations between 2001 and 2018, from the monitoring station established in Volos is used. The aim is to investigate the seasonality, intraweek, intraday, weekend effect and spatial variations of the PM<sub>10</sub> concentrations as well as trends of data, are statistically studied. The work may assist the formation of PM<sub>10</sub> forecasting models of hourly, daily, weekly, monthly and annual horizon. Significant changes observed in PM<sub>10</sub> series concentrations dusing the years were found. This may be due to economic and social reasons but also due to measures taken by the state so as to be harmonised with the European Directives concerning the protection of public health and the atmospheric environment of the European Union (EU) members.</div><div> <div> <div>Keywords: </div> PM<sub>10</sub> data series; statistical analysis; Volos; Greece</div> </div>
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Relativistic electrons (with energies >150keV) which originate in the outer radiation belt and detected by the Russian ‘Meteor’ series of satellites have been correlated with the atmospheric total ozone data compiled by almost 90... more
Relativistic electrons (with energies >150keV) which originate in the outer radiation belt and detected by the Russian ‘Meteor’ series of satellites have been correlated with the atmospheric total ozone data compiled by almost 90 stations located around the world within the latitude zone 40°–70°N. In more than 60% of the stations examined we have detected a clear decrease of the
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Introduction.- Meteorology.- Climatology.- Atmospheric Physics.- Biometeorology/Bioclimatology.- Extreme Weather Phenomena.- Remote Sensing.
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This study presents and analyzes the trends and variability of precipitation totals within the Mediterranean region, for the period 1980 - 2009, by using Global Precipitation Climatology Project (GPCP) gridded datasets and ground based... more
This study presents and analyzes the trends and variability of precipitation totals within the Mediterranean region, for the period 1980 - 2009, by using Global Precipitation Climatology Project (GPCP) gridded datasets and ground based observations from the Hellenic National Meteorological Service (HNMS) and the World Climate Data and Monitoring Programme (WCDMP) of the World Meteorological Organization. Besides, the trends of sea surface temperature (SST) and sea surface pressure (SLP) from NCEP/NCAR Reanalysis are investigated in order to explain the observed trends in precipitation. On the other hand, the influence of atmospheric circulation, by means of North Atlantic Oscillation Index (NAOI), on the precipitation variability is presented. The results showed that an anti-correlation, (statistically significant at 95% confidence level), exists between precipitation (mm/day), rain days and NAOI, within the rain season of the year (October-March), against a positive correlation within the dry season (April-September). Concerning the temporal distribution of precipitation, decreasing trends appear throughout the Mediterranean, especially in the eastern parts and within the rain season of the year, while these trends are positive within the dry period, but statistically insignificant (95% confidence level). Increasing trends of SST for both rain and dry season, and decreasing trends of SLP appear.
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Page 1. Chapter 10 Weather, Ambient Air Pollution and Bronchial Asthma in Athens, Greece Panagiotis Th. Nastos Abstract The associations between various meteorological parameters, concen-trations of PM10, SO2, and ...
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Research Interests: Environmental Science, Methodology, Climatology, Time Series, Neural Networks, and 15 moreVulnerability, Multidisciplinary, Artificial Neural Networks, Models, Statistical Significance, Projects, Precipitation, Mediterranean region, Coefficient of Determination, Indexation, Artificial Neural Network, Cumulant, Mean Squared Error, Statistical Method, and Root mean square error
Research Interests: Environmental Engineering, Environmental Science, Remote Sensing, Seasonality, Atmospheric sciences, and 9 moreAerosol, Geomatic Engineering, Remote Sensing of the Nearshore Environment, Optical Properties, Seasonal variation, Precipitation, Atmospheric Dispersion, Eastern Mediterranean, and Aerosol Optical Depth
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ABSTRACT
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Kriging interpolation technique is adapted to create the mapping of surface ozone seasonality and trends across Europe during 1997–2006, based on European Monitoring and Evaluation Programme ground measurements. The climatology, the... more
Kriging interpolation technique is adapted to create the mapping of surface ozone seasonality and trends across Europe during 1997–2006, based on European Monitoring and Evaluation Programme ground measurements. The climatology, the annual and seasonal trends and the altitude above sea level (asl) dependence were studied as well as the relation with the North Atlantic Oscillation (NAO). The mean seasonal cycle amplitude and seasonal maximum display an increasing gradient from northwest to southeast, with high levels in Austria and eastern Mediterranean. Significantly close to 0 positive trends appear in UK, Slovakia, southern Scandinavia and Austria in winter and autumn. In Northern Hemisphere winter (December–February), about 40 % of near-surface ozone variability in the western edge of Europe may be attributed to circulation changes and ozone precursors’ transport related to NAO.
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Future changes in drought characteristics in Greece were investigated using dynamically downscaled high-resolution simulations of 5 km. The Weather Research and Forecasting model simulations were driven by EC-EARTH output for historical... more
Future changes in drought characteristics in Greece were investigated using dynamically downscaled high-resolution simulations of 5 km. The Weather Research and Forecasting model simulations were driven by EC-EARTH output for historical and future periods, under Representative Concentration Pathways 4.5 and 8.5. For the drought analysis, the standardized precipitation index (SPI) and the standardized precipitation-evapotranspiration index (SPEI) were calculated. This work contributed to achieve an improved characterization of the expected high-resolution changes of drought in Greece. Overall, the results indicate that Greece will face severe drought conditions in the upcoming years, particularly under RCP8.5, up to 8/5 y of severity change signal. The results of 6-month timescale indices suggest that more severe and prolonged drought events are expected with an increase of 4 months/5 y, particularly in areas of central and eastern part of the country in near future, and areas of the...
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Climate change has led to national, regional and local adaptation measures. However, these measures are not usually implemented in a targeted way, i.e. in urban areas with the most significant problem, or they are not designed in the... more
Climate change has led to national, regional and local adaptation measures. However, these measures are not usually implemented in a targeted way, i.e. in urban areas with the most significant problem, or they are not designed in the optimal way to have the maximum efficiency at local scale. Towards this perspective the evaluation of human thermal stress in different urban environments, using appropriate models at very high resolution is considered fully appropriate. The assessment and quantification of the thermal comfort for selected urban districts within the wider Athens area, are performed by the application of PET (Physiologically Equivalent Temperature) and UTCI (Universal Thermal Climate Index) indexes, which are based on the energy balance of the human body. The above indexes are calculated with the computational fluid dynamics (CFD) model ENVI-met, at city scale (resolution 1 × 1m). Measurements from the nearest meteorological stations as well as sub-scaling of the ERA5 da...
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Climate change affects the severity and frequency of natural disasters, mainly because the positive trends in global surface temperatures increase the possibility of more droughts and also the increased intensity of rainfall leads to... more
Climate change affects the severity and frequency of natural disasters, mainly because the positive trends in global surface temperatures increase the possibility of more droughts and also the increased intensity of rainfall leads to intense flood phenomena.The Municipality of Ermionida, located in the Argolis regional unit (Peloponnese, Greece), is an area that only slightly affected by the climate crisis. The area is particularly dry, and suffers from several flash flood events especially during autumn and early winter months, thus, there is a need for a forecasting system operation at local scale.In the frame of this work, SMILE project’s objectives (which is funded by Greek Government) are presented, as well as, the general scheme of a proposed tool that is equipped with a monitoring system is described in detail. SMILE system for the Municipality of Ermionida is a user friendly online tool, designed with the scope of monitoring and processing data from connected sensors, i.e., ...
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Nisyros Geopark, an island geopark in the Southeastern Aegean Sea, Greece, is here presented as an official candidate for the UNESCO Global Geoparks designation, featuring outstanding geological, natural and cultural characteristics... more
Nisyros Geopark, an island geopark in the Southeastern Aegean Sea, Greece, is here presented as an official candidate for the UNESCO Global Geoparks designation, featuring outstanding geological, natural and cultural characteristics tightly connected to its volcanic origin. It covers a total area of 481 km2 and includes Nisyros, an active volcano and the main island, the surrounding islets of Pachia, Strongyli, Pergousa, Kandeliousa and the marine region among them. It features 24 geosites and a network of well-established walking trails. Furthermore, there are two internationally designated Natura 2000 areas covering its entire surface and also exceptional archaeological and cultural sites, including fortresses, remnants of ancient habituations and numerous churches and monasteries. It is the only area in the broader region of the Eastern Mediterranean that hosts all these features within such a restricted area. The initial efforts of the management body of Nisyros Geopark and its ...
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The assessment and interpretation of an extreme hydrometeorological event and the consequent impacts such as flash floods, especially within urban environment, is of high interest, especially in the Anthropocene era. Global warming... more
The assessment and interpretation of an extreme hydrometeorological event and the consequent impacts such as flash floods, especially within urban environment, is of high interest, especially in the Anthropocene era. Global warming intensifies Urban Heat Island resulting in local intense convective precipitation over a densely urbanized area. Urbanization on one hand, increases the sensible heat flux and transports more water vapor, mixing it into the upper atmosphere and on the other hand, increases the surface roughness and as a consequence mechanical turbulence drives low-level convergence resulting in enhanced intensity and frequency of convectional extreme precipitation (Nastos and Zerefos, 2007; Li et al., 2023).In this study, we focus on an extreme summer convective event on August 24, 2022, in Athens, Greece, where the precipitation intensity reached instantly 116 mm/h and the visibility was limited to 600m. More specifically, we analyzed and compared the H03B product of E...
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Water leakage is acknowledged as one of the most important issues that drinking water supply systems are facing worldwide. Non-Revenue Water is estimated to 346 million m3 per day and its cost/value is estimated to 39 billion USD per... more
Water leakage is acknowledged as one of the most important issues that drinking water supply systems are facing worldwide. Non-Revenue Water is estimated to 346 million m3 per day and its cost/value is estimated to 39 billion USD per year. At the same time drinking water quality is jeopardized from the water intake points to the consumer’s tap, even during normal operating conditions.ICT support water utility operators to improve the operational capacity of their water supply system. A smart green system to control water leakage and monitor drinking water quality in the water supply system of Paramythia city will be built in the context of SMASH project. It consists of: (a) IoT system comprising three local control stations, installed in selected parts of the water supply network, monitoring water quantity&quality parameters in real time; (b) the hydraulic simulation model of the water supply system of Paramythia; (c) a virtual sensors system, which will be used for water quality pr...
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<p>Climate and weather are significant factors in planning to visit a touristic destination, especially taking into consideration the global warming. In this respect, touristic areas will be significantly affected by... more
<p>Climate and weather are significant factors in planning to visit a touristic destination, especially taking into consideration the global warming. In this respect, touristic areas will be significantly affected by the potential adverse effects of climate change. This is the case of the Mediterranean which is considered one of the most vulnerable regions in global climate change, regarding the observed but also the expected future thermal risk. The goal of this study is to highlight the bioclimatic conditions anticipated to prevail in the eastern Mediterranean, studying five touristic destinations; namely, Heraklion, Crete Island (Greece), Antalya (Turkey), Limassol (Cyprus), Valletta (Malta) and Cairo (Egypt).</p><p>One of the most popular and widely applied human thermal index, the Physiologically Equivalent Temperature (PET), based on human energy balance, is utilized to quantify the regime of present and simulated future bioclimatic conditions. Air temperature, humidity, wind speed and global solar radiation (estimated at 1.1m where is the gravity center of the human body and builds the reference level for human biometeorological studies) are the parameters needed for the assessment of PET, using the RayMan model. The meteorological datasets concern 3-hour data from the SMHI RCA4 regional climate model (Rossby Center, Swedish Meteorological and Hydrological Institute, Norrkoping Sweden, spatial analysis 11 km), for the historical period 1971-2000 (reference period), as well as for the periods 2021-2050 and 2071-2100 under the two Representative Concentration Pathways, RCP4.5 (intermediate) and RCP8.5 (extreme).</p><p>As far as the historical period is concerned, the findings of the analysis showed that Heraklion, Crete Island, appears the most favorable bioclimatic conditions at midday (UTC 12:00), followed by Limassol and Malta, while Cairo and Antalya show high frequency and duration of strong/extreme heat stress within the year. Regarding evening hours (UTC 21:00) during summertime, there is a slight cold stress/thermal comfort in Heraklion and Malta, followed by Limassol, Antalya and Cairo with worse bioclimatic conditions.</p><p>Based on climate model simulations for 2021-2050 (near future) and 2071-2100 (far future) under RCP4.5 and RCP8.5, for midday (UTC 12:00), Heraklion, Crete Island depicts the best bioclimatic conditions, which can be attributed to the increased frequency and intensity of the Etesians winds, blowing during the summer period of the year contributing to the mitigation of the strong/extreme heat stress. The frequency and the duration of thermal comfort in the evening (UTC 21:00) is expected to increase for both RCPs. Malta shows similar bioclimatic behavior to Heraklion during evening hours, followed by Limassol, Antalya and Cairo, where the light/moderate heat stress occurs with increasing frequency and seasonality.</p><p>The results of the bioclimatic analysis will help in the management/dissemination of climate information for tourism purposes. In addition, the methodology used, based on bioclimatic (PET) diagrams, can provide detailed information in order to assess and quantify the climate change impacts on the tourism potential in the eastern Mediterranean.</p>
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<p>The ability of three-dimensional dust models to accurately represent the dust life... more
<p>The ability of three-dimensional dust models to accurately represent the dust life cycle is crucial for describing dust effects on radiation and clouds and for reducing the uncertainties on these processes. To improve the reliabilty of dust models, it is therefore imperative to carry out thorough evaluations of the dust properties. Dust optical and microphysical properties are accurately accessed through groundbased observations: multiwavelength lidars and sunphotometers. In this study we use the Generalized Retrieval of Atmospheric and Surface Properties (GRASP) data algorithm that combines the lidar and sunphotometer data to retrieve dust properties. GRASP is applied on a Saharan dust episode over Finokalia, Crete in Greece, on 14 May 2017. More precisely the measurements from PollyXT lidar participating in the European Aerosol Research Network (EARLINET) and the CIMEL sunphotometer participating in Aerosol Robotic Network (AERONET) are synergetically combined using the GRASP algorithm. The dust event is fully characterised through the retrieval of dust optical and microphysical properties. The retrieved properties are found to be in good agreement with the initial measurements from the AERONET sunphotometer and the lidar. Then the aforementioned tools are used to evaluate the performance of the regional dust model NMME-DREAM that has been developed to simulate and predict the atmospheric cycle of mineral dust aerosols. It is shown that the model has problems in simulating the high dust concentration values at low levels, probably due to the low spatial resolution of the model that causes difficulties in capturing the orography and the downdrafts winds.</p>
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The Predicted Mean Vote (PMV) and the Predicted Percentage of Dissatisfied (PPD) indices are used to assess the indoor environment in terms of human thermal comfort-discomfort. In this study, an experimental combined objective and... more
The Predicted Mean Vote (PMV) and the Predicted Percentage of Dissatisfied (PPD) indices are used to assess the indoor environment in terms of human thermal comfort-discomfort. In this study, an experimental combined objective and subjective investigation of thermal comfort perception has been performed in students between 16-18 years old, in a non-air-conditioned school building. The objective approach included instrumentation measurements and data processing according to ISO 7730, whereas, the subjective one was based on answers collection following ISO 10551. The study is mainly devoted to the verification of Fanger’s approach in a building, in free running conditions, under a mild (moderate) climate.The comparison between instrumentation data and questionnaire results presented an underestimation of the mean vote, predicting a cooler sensation than the actual one.
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Abstract Recent research revealed that western Greece and NW Peloponnese are regions that favor prefrontal tornadic incidence. On March 25, 2009 a tornado developed approximately at 10:30 UTC near Varda village (NW Peloponnese). Tornado... more
Abstract Recent research revealed that western Greece and NW Peloponnese are regions that favor prefrontal tornadic incidence. On March 25, 2009 a tornado developed approximately at 10:30 UTC near Varda village (NW Peloponnese). Tornado intensity was T4–T5 (TORRO scale) and consequently caused an economic impact of 350,000 € over the local society. The goals of this study are: (i) to analyze synoptic and remote sensing features regarding the tornado event over NW Peloponnese and (ii) to investigate the role of topography in tornadogenesis triggered under strong synoptic scale forcing over that area. Synoptic analysis was based on the European Centre for Medium-Range Weather Forecasts (ECMWF) data sets. The analysis of daily anomaly of synoptic conditions with respect to 30 years' climatology (1981–2010), was based on the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis data sets. In addition, numerous remote sensing data sets were derived by the Hellenic National Meteorological Service (HNMS) weather station network in order to better interpret the examined tornado event. Finally, numerical modeling was performed using the non-hydrostatic Weather Research and Forecasting model (WRF), initialized by ECMWF gridded analyses, with telescoping nested grids that allow the representation of atmospheric circulations ranging from the synoptic scale down to the meso-scale. The two numerical experiments were performed on the basis of: (a) the presence and (b) the absence of topography (landscape), so as to determine whether the occurrence of a tornado – identified by diagnostic instability indices – could be indicated by modifying topography. The energy helicity index (EHI), the bulk Richardson number (BRN) shear, the storm-relative environmental helicity (SRH), and the maximum convective available potential energy (MCAPE, for parcels with maximum θ e ) were considered as principal diagnostic instability variables and employed in both numerical experiments. Furthermore, model verification was conducted, accompanied by analysis of the absolute vorticity budget. Synoptic analysis revealed that the synoptic weather conditions on March 25, 2009 are in agreement with the composite synoptic climatology for tornado days over western Greece. In addition, maximum daily anomalies at the barometric levels of 500, 700, 850 and 925 hPa were found, compared to the climatology of composite mean anomalies for tornado days over western Greece. Numerical simulations revealed that the topography of NW Peloponnese did not constitute an important factor during the tornado event on March 25, 2009, based on EHI, SRH, BRN, and MCAPE analyses.
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Abstract Cloud-to-ground (CG) lightning activity recorded by the Hellenic National Meteorological Service (HNMS) Precision Lightning Network (PLN) is analysed over the wider area of Greece. In addition, the spatial and temporal... more
Abstract Cloud-to-ground (CG) lightning activity recorded by the Hellenic National Meteorological Service (HNMS) Precision Lightning Network (PLN) is analysed over the wider area of Greece. In addition, the spatial and temporal relationships between TRMM 3B42 (Tropical Rainfall Measuring Mission) datasets and lightning are presented. The analyses concern the period from January 14, 2008 to December 31, 2012. The Laboratory of Climatology and Atmospheric Environment, University of Athens, has established a detailed dataset of lightning impacts over Greece from 1895 to 2013, based on digitized archive editions of newspapers. The mean seasonal variability of CG lightning activity revealed autumn as the most dominant season with 303 LD, while the mean monthly variability of CG indicated October as the most lightning active month and May as the month with a mean of 27 LD. The mean annual spatial distribution of CG lightning per km 2 , depicted the maximum frequency over Pindus mountain range (> 7 CG/km 2 ). During the autumn season, the northern Ionian Sea experienced a mean frequency of more than 5 CG/km 2 , compared to the southern Ionian Sea and NW Peloponnesus, where values of more than 7 CG/km 2 are depicted. During the summer season, the maximum frequency appeared along Pindus mountain range, around Attica, Thessaly and central Macedonia highlands. The spatial distribution of seasonal correlations between the number of CG flashes/day and gridded (TRMM 3B42) daily rainfall totals for the period 2008–2012 over Greece, indicated that correlations were mainly positive all over the under study area, within all seasons, and especially during summer and autumn. Regarding the lightning impacts in Greece, based on the 1895–2013 study period, more than 343 fatalities and at least 224 injured people have been recorded. The spatial analysis of lightning impacts, showed that the majority of events has been recorded over Greek mainland and only few scattered events have been reported over Ionian and Aegean Seas. The results of the performed research for Greece, during 1895–2013 (2000–2013), indicated that fatalities/injuries caused by lightning, were estimated at 2.9 (2) deaths/1.9 (1.6) injuries per year, respectively.
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In the present study, an estimation of the future change in precipitation within the 21st century was carried out for the 12 climatic zones of Greece. The estimation is based on the results of 12 Regional Climate Models (RCM) simulations... more
In the present study, an estimation of the future change in precipitation within the 21st century was carried out for the 12 climatic zones of Greece. The estimation is based on the results of 12 Regional Climate Models (RCM) simulations of the ENSEMBLES Program. The precipitation is projected to decrease mildly in the near future (2021-2050) and moderately in the far future (2071-2100) by 5% and 20% respectively for the area of Greece. The decrease seems to be most prominent during spring and summer, less prominent during winter. The autumn precipitation is projected to increase mildly in the near future and to decrease mildly in the far future. The projected precipitation change in Greece is expected to result in drastic changes on the ground water balance and on several sectors of human activity and environment parameters, as well.
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The study of atmospheric models and climate systems has been hampered by the restricted availability of wind profile measurements. By recording wind profiles in near real time and giving useful information for Numerical Weather Prediction... more
The study of atmospheric models and climate systems has been hampered by the restricted availability of wind profile measurements. By recording wind profiles in near real time and giving useful information for Numerical Weather Prediction (NWP) models, the Doppler wind lidar technology used in the European Space Agency’s Aeolus mission is expected to unravel this problem. By analyzing the precipitation from IANOS medicane, which occurred over the Thessaly plain in September 2020, a case study utilizing the COSMO NWP model illustrates the potential usefulness of Aeolus data in strengthening NWP models. Run in hindcast mode and forced by analyses with and without Aeolus, the model assimilated data that were produced at the European Centre for Medium-Range Forecasts (ECMWF). Evaluation against observations from Greek synoptic stations showed that the model precipitation using the Aeolus-assimilated data preponderated over the model results without their inclusion. This work aims to dem...
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During the 1960s tourists from the West started to discover the Greek "couleur locale" including the triptych Sun, Sea and Souvlaki on the islands of the Aegean Archipelago. From these three famous S the first two have been present in the... more
During the 1960s tourists from the West started to discover the Greek "couleur locale" including the triptych Sun, Sea and Souvlaki on the islands of the Aegean Archipelago. From these three famous S the first two have been present in the region since the antiquity and the third was a food invention of the twentieth century, the Greek version of what it is called fast (and cheap) food. The climatic studies, by foreign and Greek scientists, which started in a professional level since the mid-19th century have proved, beyond any question, that the prevailing weather in the Southern Balkan Peninsula has not changed significantly for about forty centuries, despite the fluctuations which have been appeared in certain periods. In our paper we aim to discuss the connection between food and weather in the Greek speaking lands during three distinctive periods: the antiquity, the Byzantium and the period of contemporary Hellenism until the 1970s. Since this decade, other cultural, political and social parameters have altered significantly the dietary habits of the Greeks, though in some extent, especially in the countryside and the lower social classes, these changes are not so marked as in the urban centres and the middle and upper classes. Our presentation will be based on visual and textual data, like representations in pottery and paintings and narratives in prose or poems. It is our scope to examine whether or not under relatively stable weather conditions, which undoubtedly are a very important factor for the formation of a general national identity, food could be used as a tracer to investigate the so called "fine structure phenomena" like the identities of certain social groups and certain local populations. Finally, having used Greece as a case study we may propose a theoretical scheme for the use of food as a climate indicator.