Drrr quiz

• Hydrometeorological hazards are natural processes or phenomena that are of atmospheric, hydrologic, or oceanographic. These hazards may cause the loss of lives, damage to property, social and economic disruption, or environmental degradation. The geographic location of the Philippines accounts for the high frequency of occurrence of these hazards. At times, these hazards concur in a single event and varying intensities. Signs of impending hydrometeorological hazards In this module, we will focus on common hydrometeorological hazards experienced in the Philippines.
• Typhoon


  A violent tropical cyclone that forms over warm waters, North of the equator in the Western Pacific Ocean. It contains winds rotating counterclockwise, with a speed of 118-220 kilometers per hour. It could also develop into a super typhoon if the wind speed exceeds 220 kilometers per hour.
• Typhoon


  • Impending signs when close to landfall:
  • Increased ocean swell
  • Changes in clouds
  • Barometric pressure drop
  • Abrupt changes in wind speed
• Increased ocean swell


  1. A swell is a series of ocean waves brought about by strong winds

  2. An incoming typhoon would cause a swell of about a meter in height that hit the shore every 10 seconds

  3. As the typhoon approaches the waves come in much faster and may also increase in height
• Changes in clouds


  1. Cumulus clouds may fill the sky about 36 hours before a typhoon

  2. As the storm approaches, the sky could be clear of clouds and may later have a mass of cirrus clouds which appear as a veil covering the horizon, eventually covering a large portion of the sky

  3. A few hours before the typhoon landfall, low-lying clouds form which slowly become thick and dark, usually accompanied by rain
• Barometric pressure drop


  1. The atmospheric pressure may start to drop about 36 hours before typhoon landfall

  2. This will continue as the storm approaches
• Abrupt changes in wind speed

  1. Wind speed increases due to the drop in atmospheric pressure as air moves from an area with high pressure to low pressure

  2. The increase in wind speed also increases the height of the ocean swell
• Thunderstorm


  A small-scale storm accompanied by lightning and thunder. A typical thunderstorm only lasts about 30 minutes to an hour and may cover an area as small as 5 kilometers in diameter. However, they bring about other hazards such as strong winds and heavy rainfall. In extreme cases, they may be accompanied by hail or tornado.
• The impending signs of a thunderstorm include the following: 1. system of cumulonimbus clouds – unequal heating of the Earth’s surface cause the upward movement of moist air, forming a tower of cumulonimbus clouds that continuously accumulate in the sky, signaling an incoming thunderstorm (Figure 1).
• Cumulonimbus clouds

  • Filled with water droplets
  • Serve as a barrier for sunlight
  • Sky darkens with a greyish tint or may also have hues of green, yellow, or violet
  • Dark bases indicate thunderstorm clouds forming
• Lightning and thunder


  1. Flashes of lightning followed by thunder

  2. May occur even before the rain falls

  3. Thunder inaudible means thunderstorm is approaching or forming from a distance

  4. Atmosphere becoming electrically charged causes radio static
• Gusts of wind and change in wind direction


  • Downdrafts are rapidly descending air columns
  • Downbursts descend even faster and may be as strong as a tornado
• Storm surge


  Rapid rise of seawater above normal sea level on the coast, generated by strong winds brought about by typhoons and thunderstorms
• Unlike a tsunami, storm surge is a fast and unexpected hazard that can occur anytime during a storm
• Residents of low-lying coastal areas should evacuate upon observing signs of an incoming storm
• Flood


  • Land areas normally not covered with water become submerged, often after heavy and continuous rainfall
  • May be caused by temporary overflow from bodies of water, adjacent lands, or floodplains
  • Accompanied by rain
  • Watch for overflowing water from manholes
  • Flooding may last for days and even weeks
• Flashflood


  • Flood characterized by a raging current that occurs when the water level rises due to heavy rainfall
  • Lasts from a few minutes to a few hours
  • Common along rivers, mountain canyons, coastline, creeks, and even urban areas
• Impending signs of flashflood


  1. Weather forecasts typhoon or thunderstorm bringing intense and prolonged rainfall

  2. Water collecting in puddles and rapidly rising

  3. Muddy water indicating calm water has been disturbed

  4. Roaring sound from upstream of stones, branches, or logs being carried in the water

  5. Floating debris in water like twigs, leaves, and sticks from bigger branches and logs