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Moisture stress is a form of abiotic stress that occurs when the moisture of plant tissues is reduced to suboptimal levels. Water stress occurs in response to atmospheric and soil water availability when the transpiration rate exceeds the rate of water uptake by the roots and cells lose turgor pressure .
Plant stress research looks at the response of plants to limitations and excesses of the main abiotic factors (light, temperature, water and nutrients), and of other stress factors that are important in particular situations (e.g. pests, pathogens, or pollutants). Plant stress measurement usually focuses on taking measurements from living plants.
A generalized view of the heat index showing how the perception of heat by the human body increases with temperature but more rapidly at higher humidity levels. The heat index of a given combination of temperature and humidity is defined as the dry-bulb temperature which would feel the same if the water vapor pressure were 1.6 kPa. Quoting ...
The Weather Stress Index, or WSI, is a relative measure of the weather conditions, often used as a comfort indicator. The index, a number between 0 and 100, represents the percentage of time in the past with temperatures below the current temperature, for a given location, day and time.
Specific humidity (or moisture content) is the ratio of the mass of water vapor to the total mass of the air parcel. [15] Specific humidity is approximately equal to the mixing ratio, which is defined as the ratio of the mass of water vapor in an air parcel to the mass of dry air for the same parcel.
In 1907, Edgar Buckingham created the first water retention curve. [2] It was measured and made for six soils varying in texture from sand to clay. The data came from experiments made on soil columns 48 inch tall, where a constant water level maintained about 2 inches above the bottom through periodic addition of water from a side tube.
If the stress is reapplied, the soil will re-consolidate again along a recompression curve, defined by the recompression index. Soil that has been consolidated to a large pressure and has been subsequently unloaded is considered to be overconsolidated. The maximum past vertical effective stress is termed the preconsolidation stress.
The Moisture Index (Im) expresses the global moisture of the environment and is directly related with the aridity and humidity indexes. The driving factor in this system is the water budget of a region. [8] Humidity classes range from Arid to Perhumid (Thoroughly Humid).