Dr.Babu, C A; Asha, Philip S; Hareeshkumar, P V(www.elsevier.com/, January , 2007)
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Abstract:
Numerous low - pressure systems form in the Arabian Sea and Bay of Bengal. These low-pressure systems are
highly useful in bringing the rainfall over the Indian sub continent. The developments of these systems are accompanied
by the reduction in air temperature and an increase in atmospheric humidity. The radio refractivity, which is a function
of the atmospheric pressure, temperature and humidity, also changes following the development of these systems. Variation
of radio refractive index and its vertical gradient are analysed for many low pressure systems formed over the Arabian
Sea and Bay of Bengal. It is found that the atmosphere becomes super refractive associated with the formation of these
systems, caused by the increase in humidity and decrease in temperature. The maximum gradient is observed near the
surface layers, especially in the lowest 1 km. Super refraction leads to increased radar detection range and extension of
radio horizon