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thunderstorms. Their relationship with rainfall can be 
investigated to derive numerical function to estimate 
rainfall. 
• Spatial variation of wind vector. Speed and direction of 
wind can be examined as they are closely related to 
rainfall. Over the study area, showers or rain are less 
likely in a westerly airstream which trespasses over the 
neighboring land mass. Whereas, easterly airstream 
which trajectories over the sea often brings widespread 
rain. Besides, seabreeze air converging with synoptic 
wind flow forms low level convergence which causes 
general lifting of the air to form precipitating cloud. 
• Local factors other than topography. These include 
geology and vegetation which are observed to cause 
rainfall variations even over short distances. Studies can 
be conducted on the types of vegetation and soil over the 
study in spatial relationship with rainfall. 
• Area extent of precipitating cloud. It can be employed in 
determining the area of interpolation. This can be 
attempted with the cloud information observed from 
satellite imagery and radar echoes. 
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