Leaf wetness

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الموسوعة الحرة

Leaf wetness is a meteorological parameter that describes the amount of dew and precipitation left on vegetation. It is used for monitoring leaf moisture for agricultural purposes, such as fungus and disease control, for control of irrigation systems, and for detection of fog and dew conditions, and early detection of rainfall.[1]

Leaf wetness may be measured by various means:[2][3]

  • By change in electrical resistance between two metal conductors in an alternate finger[4] or double spiral[5] configuration on a flat surface, either flat or cylindrical.[6] The conductors are usually gold plated for corrosion resistance. An issue with this method is that measurements depend on droplets being large enough to bridge the gap between the conductors. A surface coating of for instance hygroscopic latex paint may be applied for more consistent results.[7][8][9] Resistance measurement is often by alternating current excitation.[10]
  • By measuring the change in the dielectric constant of the surface of a sensor, thus detecting the presence of water or ice on the sensor's surface.[11]
  • A sensor with hygroscopic properties where a change in sensor length or weight can be measured mechanically.

See also

References

  1. ↑The Leaf Surface Wetness Duration Home Page, Cornell University
  2. ↑Types of sensors, The Leaf Surface Wetness Duration Home Page
  3. ↑Some leaf wetness sensors, Campbell Scientific
  4. ↑Resistance type sensorArchived 2010-11-02 at the Wayback Machine, Davis Instruments
  5. ↑Double spiral configurationArchived 2005-06-19 at the Wayback Machine, ICT International
  6. ↑A comparison of cylindrical and flat plate sensors for surface wetness duration: Gillespie T.J., Duan R.X., 1987. Agric For Meteorol 40: 61-70.
  7. ↑Do you measure leaf wetness?, Decagon Devices
  8. ↑ تأثيرات الطلاء وزاوية النشر واتجاه البوصلة على أداء أجهزة استشعار الرطوبة الإلكترونية خلال فترات الندى : Lau, YF, Gleason, ML, Zriba, N., Taylor, SE, Hinz, PN, 2000. Plant Disease 84:192-197.
  9. ↑ مستشعر مدة رطوبة الأوراق الإلكتروني: لماذا يجب طلاؤه : سينتيلهاس، بي سي، مونتيرو، جي إي، جيليسبي، تي جيه، 2004. المجلة الدولية لعلم الأرصاد الجوية الحيوية 48: 202-205.
  10. ↑ مستشعر رطوبة الأوراق، مؤرشف بتاريخ 26 يوليو 2017 في أرشيف الإنترنت (Wayback Machine) ، LWET
  11. ↑ مستشعر رطوبة الأوراق العازل، مؤرشف بتاريخ 8 يوليو 2011 في أرشيف الإنترنت (Wayback Machine )، شركة كامبل ساينتيفيك