Soil drought can mitigate deadly heat stress thanks to a reduction of air humidity

We calculated the effective temperatures based on 10-year data for temperatures (monthly average and minimum), wind speeds (monthly average and maximum) and relative air humidity in the climatic zones of the Krasnoyarsk Territory (subarctic No. 1) and temperate continental (Krasnoyarsk (object No. 2) and Minusinsk (3) We assessed the health risk.In winter, in the subarctic zone, the temperature is –23.3 ± 1.5 0 C (minimum –30.2 ± 2.1 0 C), in object No. 2 — –17.3 ± 1.6 0 C (–19.3 ± 1.0 0 С) and object No. 3 — –19.9 ± 1.4 0 С (–25.5 ± 1.9 0 С). In spring at object No. 1 it varied from –16.5 ± 1.7 0 С to + 1.6 ± 1, 0 0 С, object No. 2 — from –3.9 ± 0.9 0 С to + 9.4 ± 0.5 0 С, object No. 3 — from –4.5 ± 0.9 to + 10.6 ± 0.4. Temperatures ranged from + 8.2 ± 0.9 0 C to –17.8 ± 1.2 0 C (object No. 1), from + 9.4 ± 0.5 0 C to –7.5 ± 0.9 0 C and from +10.4 ± 0.4 0 C to –6.4 ± 1.0 0 C. In summer, the temperature was 19.9 ± 0.9 0 C, 18.8 ± 0.3 0 C, and 19.8 ± 0.4 0 C, respectively. Wind speed at object No. 3.6 ± 0.05 m/s in July increased to 5.4 ± 0.2 m/s in December (maximum 16.2 m/s); No. 2 in July 1.4 ± 0.05 m/s, in October-May 1.8 ± 0.2–2.1 ± 0.07 (maximum in December 10.1 ± 0.1 m/s); No. 3 minimum wind in January and February (1.1 ± 0.1 m/s), maximum 10.7 ± 0.6 m/s in May. A moderately dry climate is recorded during 2, 4 and 5 months. In the conditions of Krasnoyarsk and Minusinsk in the spring, humidity drops to the limits of dry air. Average effective temperatures indicated a possible risk of frostbite in the subarctic zone after 20–30 minutes within 2 months; at minimum temperatures and maximum winds in March, frostbite in 20–30 minutes, in November, December and February in 10–25 minutes; in January — in 5 minutes. In the Krasnoyarsk region in January frostbite is possible within 20–30 minutes, in Minusinsk in February in 20–30 minutes, in January 10–15 minutes. Heat stress is undefined.

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A light-induced decrease in the photochemical reflectance index (PRI) can be used to estimate the energy-dependent component of non-photochemical quenching under heat stress and soil drought in pea, wheat, and pumpkin

Photosynthesis Research ◽

10.1007/s11120-020-00718-x ◽

2020 ◽

Vol 146 (1-3) ◽

pp. 175-187 ◽

Cited By ~ 5

Author(s):

Lyubov Yudina ◽

Ekaterina Sukhova ◽

Ekaterina Gromova ◽

Vladimir Nerush ◽

Vladimir Vodeneev ◽

...

Keyword(s):

Heat Stress ◽

Photochemical Quenching ◽

Soil Drought ◽

Photochemical Reflectance Index ◽

Dependent Component ◽

Non Photochemical Quenching ◽

Energy Dependent

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The influence of air humidity on human heat stress in a hot environment

International Journal of Occupational Safety and Ergonomics ◽

10.1080/10803548.2019.1699728 ◽

2020 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Andrzej Sobolewski ◽

Magdalena Młynarczyk ◽

Maria Konarska ◽

Joanna Bugajska

Keyword(s):

Heat Stress ◽

Air Humidity ◽

Hot Environment

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Forecasting Heat Stress in Dairy Cattle in Selected Barn Zones with the Help of Thi and Thiadj Indexes / Prognozowanie Stresu Cieplnego U Bydła Mlecznego W Wybranych Strefach Obory Za Pomocą Wskaźników Thi I Thiadj

Annals of Animal Science ◽

10.2478/aoas-2013-0029 ◽

2013 ◽

Vol 13 (4) ◽

pp. 837-848 ◽

Cited By ~ 4

Author(s):

Piotr Herbut ◽

Sabina Angrecka

Keyword(s):

Heat Stress ◽

Solar Radiation ◽

Air Humidity ◽

Movement Velocity ◽

Air Movement ◽

Relative Air Humidity ◽

Microclimatic Conditions ◽

Hot Weather ◽

The Impact ◽

Occupied Zone

Abstract The paper presents the influence of temperature, relative air humidity, air movement velocity and solar radiation on forecasting the risk of heat stress in dairy cows in a free-stall barn during hot weather seasons. THI and adjusted THI indexes were calculated for the periods in which the air temperature exceeded 28°C in the barn, and when it reached 25°C. Based on the THI values obtained during the heat, which ranged from 63 to 83, the occurrence of heat stress in cattle was stated. Heat stress also caused a decrease in milk yield, from about 22 kg to about 18 kg in the technological group. The calculated THIadj values (83 to 90), taking into account the solar radiation and air movement velocity, indicated also the occurrence of health-threatening conditions for cattle. On the fourth day of heat the maximum daily value of THI in the first measurement point was 83 with THIadj of 90, while in the second point THI was 82 and THIadj was 87. This indicated the occurrence of significant differences in microclimatic conditions in the occupied zone of the same technological group. The influence of investigated microclimate factors on the formation of THIadj in the researched zone of the barn was stated. No proper method of its determination was also stated. The analysis of the impact of air movement velocity on THIadj value (P<0.05) and the solar radiation (P<0.05) demonstrated the importance of these parameters in forecasting heat stress in cows in the barn.

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The effect of soil-moisture on human heat stress during hot spells

10.5194/egusphere-egu2020-11530 ◽

2020 ◽

Author(s):

Hendrik Wouters ◽

Diego G. Miralles ◽

Jessica Keune ◽

Irina Y. Petrova ◽

Adriaan J. Teuling ◽

...

Keyword(s):

Soil Moisture ◽

Heat Stress ◽

Air Temperature ◽

Land Surface ◽

Large Scale ◽

Detrimental Effect ◽

Mechanistic Model ◽

Air Entrainment ◽

Air Humidity ◽

Hot Spells

Hot extremes are typically instigated by a combination of favorable large-scale conditions and positive land surface feedbacks: as heatwaves evolve, the soil dries out and the decreased evaporation is accompanied by further heating of the atmosphere. Extreme high temperatures are known to cause increased mortality, and thus dry soils are typically thought to be associated with higher risk for human health. However, empirical studies indicate that health-threatening consequences and overall human discomfort during heatwaves not only depend on air temperature, but on air humidity as well. Drying soils are expected to reduce air humidity, which may &#8212; to a yet-unknown degree &#8212; offset the detrimental effect of soil dryness on increased temperatures in what relates to human heat discomfort. Here, we provide observational evidence for the role of anomalies in soil moisture on heat stress worldwide. We use a novel framework that combines weather balloons, reanalysis and satellite data with a mechanistic model of the atmospheric boundary layer. The health-threatening nature of hot spells is diagnosed by adopting a definition based on the concept of wet-bulb temperature and findings from recent meta-analysis of global human lethal impact data. Results indicate that the detrimental effect of drying soils on air temperature is overcompensated by the beneficial effect on reduced air humidity, which is partly related to the enhanced dry air entrainment. These findings can be used to design climate change adaptation strategies, being aware that ongoing trends in land and atmospheric dryness will impact human heat stress during future heatwaves.

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Effect of Relative Air Humidity and High Temperature on the Physiological and Anatomical Responses of Two Rhododendron Cultivars

HortScience ◽

10.21273/hortsci13974-19 ◽

2019 ◽

Vol 54 (7) ◽

pp. 1115-1123

Author(s):

Wenjie Ma ◽

Wen Liang ◽

Bing Zhao

Keyword(s):

Heat Stress ◽

High Temperature ◽

Vapor Pressure ◽

Enzymatic Activity ◽

Stomatal Density ◽

Total Chlorophyll ◽

Air Humidity ◽

Total Chlorophyll Content ◽

Relative Air Humidity ◽

Relative Water

The effects of different relative air humidity (RH) levels under high temperature and accompanying vapor pressure deficits (VPDs) on the physiology, photosynthesis, and anatomy of Rhododendron need to be better understood to help in reducing damage to leaves caused by high temperature. In this study, two Rhododendron cultivars were exposed at 45%, 55%, 65%, 75%, and 85% RH to a treatment of constant temperature at 38 °C for 14 days, resulting in a VPD of 3.64, 2.98, 2.32, 1.66, and 0.99 kPa, respectively. The results showed the least reduction of the net photosynthetic rate (Pn) under 75% RH treatment in R. ‘Fen Zhenzhu’ (decreased by 79.8%), and under the 85% RH treatment in R. ‘Zhuangyuan Hong’ (decreased by 75.4%). The decline in relative water content (RWC) was less under the 75% and 85% RH treatments, and electrolyte leakage showed a slight decrease under the 75% RH treatment in the two Rhododendron cultivars. The appearance of the two cultivars under greater RH showed less damage, probably because plants can avoid damage by increasing total chlorophyll content, decreasing stomatal area, stomatal density, and opened stomata ratio, enhancing enzymatic activity and osmoregulation substances, and improving leaf structure. The findings show that greater RH can alleviate damage caused by heat stress and improve thermostability.

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