Specialists from the Hydrometeorological Service Agency of Uzbekistan (Uzhydromet) organized a press tour for journalists, explaining how air temperature is measured in the country, why official data differs from street thermometer readings, and to what extent reports of “temperature records” circulating on social media can be trusted. At 10:00 AM, when everyone gathered at the meteorological site of the Tashkent Observatory, the air temperature was +36.2 degrees Celsius.
The meeting place was chosen for a reason. It is here that meteorological data is recorded, which is later used in official weather forecasts. “All measurements are carried out in strict accordance with the standards of the World Meteorological Organization (WMO). Data is taken every three hours starting from midnight Greenwich Mean Time,” says Khojiakbar Odilov, chief specialist of Uzhydromet.
First, he showed the psychrometric booth — a wooden box with louvers instead of solid walls. Inside are four thermometers. One shows the current air temperature. The second, wrapped in a wet cloth, is used to calculate humidity. The other two — maximum and minimum thermometers — record the highest and lowest readings between measurements.
The louvers ensure constant air circulation. If air does not circulate, the temperature inside the booth begins to differ from the ambient temperature, and such readings cannot be correctly compared with data from other weather stations. The booth is installed at a height of 2 meters above the ground. This is an international WMO standard. Using the same height at all weather stations allows comparison of data worldwide. Additionally, 2 meters is close to the height at which humans breathe.
As explained by Khusan Tursunov, at this height the influence of the earth's surface is minimal. During the day, the soil heats up quickly, and at night it cools down quickly. Therefore, a thermometer installed at a height of 10–20 cm from the ground would measure soil temperature rather than air temperature. Next to the psychrometric booth, an automatic weather station is also installed. It independently measures air temperature, relative humidity, atmospheric pressure, solar radiation, wind speed, and direction.
“Previously, an observer would record readings every three hours. Now the station independently sends data to the server every 10 minutes. There is no human factor in its operation,” says Odilov. According to him, 117 such stations operate in Uzbekistan. They are installed in almost every district, and some districts have two or three.
The difference between the readings of the automatic station and the psychrometric booth does not exceed 0.2 degrees. This is usually due to the installation location and instrument characteristics. Nevertheless, the psychrometric booth is still necessary. Tursunov noted that classical psychrometers are used to control automatic sensors. Since errors or malfunctions may occur over time, their readings are regularly checked.
Furthermore, the aspiration psychrometer remains the reference method for measuring humidity. At many stations, observations have been conducted using this method for decades. Therefore, new data from automatic stations must be compared with long-term observation series. Wind speed and direction are measured separately — at a height of 10 meters. This also complies with international standards.
Air humidity is not measured directly but is calculated. The second thermometer in the psychrometric booth, wrapped in a wet cloth, shows not humidity but the evaporation temperature. The difference between the readings of the dry and wet thermometers is analyzed using psychrometric tables, and the exact humidity value is determined.
Soil temperature is measured on a separate site in the southern part of the station. Thermometers are installed at depths from 5 cm to 3.2 m. This data is mainly used in agriculture, as well as for preparing winter forecasts regarding soil freezing and groundwater conditions. Precipitation is measured in two ways — traditional and automatic. In the first case, rainwater collected in a special container is poured into a measuring cup, and its amount is determined in millimeters. In the second case, these measurements are performed automatically by a special device.
All data from weather stations is transmitted to a single system, on the basis of which weather forecasts are prepared. Data from all meteorological stations in Uzbekistan is combined with data from neighboring countries. It is then processed using mathematical models that calculate the development of weather processes.
Experts also explained the cause of the current heatwave. According to them, since July 13, hot air masses have been entering Uzbekistan from the south and are expected to persist at least until the end of the week. In some regions, air temperatures reach +41…+43 degrees, and in central and southern regions — +43…+44 degrees. Khusan Tursunov explained that this is part of a seasonal phenomenon called summer thermal depression, which forms over Central Asia.
“During this period, the highest temperatures of the year are observed in the republic. This phenomenon occurs in late June, July, and early August. Among the people, this period is called 'chilla',” said Tursunov. He emphasized that the current heatwave is not record-breaking. The highest temperature in the history of observations in Uzbekistan was recorded in July 1983 in the village of Ayakagitma, Bukhara region, reaching +49.9 degrees. This absolute maximum has been maintained for over 40 years.
In Tashkent, the temperature record was set on July 18, 1997, when the air warmed up to +44.6 degrees. The temperature expected this week will not reach this level. Experts urged not to take reports of +50 degrees and above regularly circulated on social media as proof of errors in official forecasts. They noted that the difference between street thermometer readings cited online and official data is explained by the specifics of the measurement method.
The meteorological service measures air temperature based on international standards — in the shade, at a height of 2 meters from the ground, in a ventilated booth. Thermometers on a car dashboard, on hot asphalt, or on a balcony exposed to direct sunlight naturally show higher temperatures. However, this is the result of surface heating, not air heating. Therefore, comparing such readings with official meteorological data, especially extreme temperatures recorded, for example, in Death Valley, is incorrect.
Commenting on reports of tragic incidents in Europe due to unusual heat, experts noted that the same air temperature can affect people's health differently. One of the main reasons is air humidity. When humidity is high, it is more difficult for the body to cool down through sweat evaporation. The dry climate of Central Asia usually allows for easier tolerance of heat.
According to Uzhydromet's operational data, on July 18–20, very hot air will continue to flow into Uzbekistan from the south. Temperatures are expected to rise to +43…+45 degrees, and in the south and desert areas, locally up to +46…+48 degrees. Earlier, Gazeta published recommendations from the World Health Organization on how to protect oneself from the heat. These include avoiding the sun during the hottest part of the day, drinking more water, closing windows during the day to prevent sunlight from entering, as well as not leaving children in closed cars and not covering baby strollers with cloth.
Source: www.gazeta.uz