colony of rats on the surface and almost certainly numerous complaints to the control agency. In short, the uncontrolled populations of rats in sewers constitute a reservoir which extends into all parts of a city and is capable of establishing new infestations on the surface. The structural damage caused by sewer rats can be considerable. They are
The Saffir-Simpson scale measures the intensity of a hurricane. Wind speed is measured on a scale of 1-5 to give an estimate of potential property damage and flooding along the coast. The Categories are as follows: Category One Hurricane: Winds 74-95 mph.
High and low pressure. High and low pressure systems cause the day-to-day changes in our weather. In this article we look at how they are defined and how they form. The Earth's atmosphere exerts a pressure on the surface. Pressure is measured in hectoPascals (hPa), also called millibars. Standard pressure at sea level is defined as 1013hPa, but we can see large areas of either high or low pressure.