Thunderstorm

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  Thunderstorm, a violent short-lived weather disturbance that is almost always associated with lightning, thunder, dense clouds, heavy rain or hail, and strong gusty winds. Thunderstorms arise when layers of warm, moist air rise in a large, swift updraft to cooler regions of the atmosphere. There the moisture contained in the updraft condenses to form towering cumulonimbus clouds and, eventually, precipitation.  Columns of cooled air then sink earthward, striking the ground with strong downdrafts and horizontal winds. At the same time, electrical charges accumulate on cloud particles (water droplets and ice).  Lightning discharges occur when the accumulated electric charge becomes sufficiently large. Lightning heats the air it passes through so intensely and quickly that shock waves are produced; these shock waves are heard as claps and rolls of thunder. On occasion, severe thunderstorms are accompanied by swirling vortices of air that become concentrated and powerful en...
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Floods

 Floods are the most frequent type of natural disaster and occur when an overflow of water submerges usually dry land. Floods are often caused by heavy rainfall, rapid snowmelt, or a storm surge from a tropical cyclone or tsunami in coastal areas.


Floods can cause widespread devastation, resulting in loss of life and damages to personal property and critical public health infrastructure. Between 1998-2017, floods affected more than 2 billion people worldwide. People who live in floodplains or non-resistant buildings, or lack warning systems and awareness of flooding hazards, are most vulnerable to floods.        













  • Flash floods are caused by rapid and excessive rainfall that raises water heights quickly, and rivers, streams, channels, or roads may be overtaken.

  • River floods are caused when consistent rain or snow melt forces a river to exceed capacity.


    • Between 80-90% of all documented disasters from natural hazards during the past 10 years have resulted from floods, droughts, tropical cyclones, heat waves, and severe storms. Floods are also increasing in frequency and intensity, and the frequency and intensity of extreme precipitation are expected to continue to increase due to climate change.

    • Drowning accounts for 75% of deaths in flood disasters. Flood disasters are becoming more frequent and this trend is expected to continue. Drowning risks increase with floods, particularly in low- and middle-income countries where people live in flood-prone areas, and the ability to warn, evacuate, or protect communities from floods is weak or only just developing. 







Floods can also have medium- and long-term health impacts, including:

  • water- and vector-borne diseases, such as cholera, typhoid or malaria

  • injuries, such as lacerations or punctures from evacuations and disaster cleanup 

  • chemical hazards

  • mental health effects associated with emergency situations

  • disrupted health systems, facilities and services, leaving communities without access to health care 

  • damaged basic infrastructure, such as food and water supplies, and safe shelter.

  • ensure appropriate food supplementation 

  • restore primary care services, like immunization, child and maternal health, and mental health

  • assemble mobile health teams and outreach

  • conduct epidemic surveillance, early warning and response

  • call for emergency funding to support health action.







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