Meteorological and Hydrological Hazards

Vocabulary The Equator: an imaginary line that separates the world into a northern and southern have Saffir-Simpson Scale: scale from 1 to 5 that measures a hurricane’s force Greenhouse effect: the warming of the layer of air surrounding the Earth due to pollution Urbanization: the movement of the population into city life Deforestation: the removal of a forest or stand of trees where the land is thereafter converted to a non-forest use. 

Meteorological Disaster: Hurricanes Hurricanes are also called severe tropical cyclones or typhoons They are exceptionally strong tropical storms These storms develop along the equator. They are giant whirlwinds that are 100 to 500 kms wide They occur when the temperature at the waters surface rises above 26 degrees Celsius and wind speeds exceed 117 km/h

Saffir- Simpson Scale

Hydrological Hazards: Floods Floods are natural disasters that occur when rain is both heavy (50-70 mm/h) and continuous(over 200 mm in 24h) This causes and unusual rise in water levels Flooded streets make it difficult for rescue workers to reach victims and transport supplies The force of the water destroys fragile buildings and damages property

Natural Hazards and Humans During the 1990’s the centuries highest temperatures this century were recorded During the summer of 2003 an unusual heat wave swept through Europe killing 21000 people. Mostly the elderly and the sick Since the end of the 1960’s snowfall has decreased by 10-15 percent Since 1980 the Arctic has lost almost 10 percent of its layer of sea ice Since the end of the 19th century the Earth has warmed by 0.4 to 0.8 degrees and sea levels have risen to 10-20 cm

Major cause 1: Greenhouse Gases Three main gases lead to the greenhouse effect Carbon Dioxide: from burning fossil fuels Methane: gas leaks, pig farms and decomposing waste materials Chlorofluorocarbons: used in refrigerators, air conditioners and aerosol cans Most scientists believe that humans must decrease the use of these gases If they don’t these gases can cause major weather upheavels such as hurricanes, flooding and drought which could be bad for life on earth

Cause 2: Urban Development Environmental modifications and development along coastal areas are increasing the risk of flooding Water proof asphalt and buildings allow the water run off during rain fall, and less trees in the cities mean the water is not absorbed allowing water to rise quicker Highways act as canals and allow floods to spread further and faster than before by changing their natural pathways

Cause 3: Deforestation Deforestation modifies the water cycle by changing the soils capacity for absorbing and storing water Deforestation increases the risk of landslides