According to VASAT (2013), rainfall is occurred when the moisture at the atmosphere condenses into water drops. Rainfall will fall towards the grounds when the water drops is too heavy to stay aloft. Hubbart (2011) described hydrologic cycle which also known as water cycle as a conceptual model that describes the storage and movement of water between the biosphere, atmosphere, lithosphere and hydrosphere. Figure 2.1 illustrates the hydrological cycle. Three types of rainfall are convectional rainfall, cyclonic rainfall and orographic rainfall (Rakhecha and Singh, 2010; Das and Saikia, 2009). Malaysia generally experiencing convectional rainfall where the rainfalls were usually very intense and normally will lasts more than two hours (Department of Irrigation and Drainage, 1986; Putra World Trade Centre, n.d.). In addition, convectional rainfall is often …show more content…
These characteristics are affected by few factors such as latitude, altitude, and level of humidity. Besides that, La nina or El nino also affecting rainfall. According to Malaysian Meteorological Department (n.d.), every two to seven years, a warm current of water replaces the usual cold current of water off the west coast of Peru, South America. This phenomenon is called El Nino and lasts for 6 to 18 months. During this period, the warmer water in the central and eastern Pacific supplies the atmosphere above it with additional heat and moisture. This will favors strong rising motion and results in lower atmospheric surface. As a result, phenomenon called La Nino is occurring where the rising moist air condenses to form large areas of thunderstorm clouds and heavy rainfall in the area. Malaysian Meteorological Department (n.d.) also stated that in the western part of the Pacific including Malaysia, atmospheric pressure increase, thus resulting in relatively drier weather. This phenomenon is called El