Tornadoes

• what are most tornadoes associated with?

  a parent thundercloud
• what are tornadoes called before they begin to spin and hit the ground?

  funnel clouds
• why are tornadoes visible?

  due to a condensation funnel of dust and debris which is picked up as it rotates
• what is the scale of the effects like?

  very localised but very destructive
• where have tornadoes been documented?

  on every continent other than Antarctica
• where are tornadoes the most common?

  America
• how many tornadoes does America see annually?

  over 1000
• why are tornadoes the most sought after disaster, despite being so dangerous?

  storm chasing and tourism
• what is a tornado?

  a localised area of violently rotating air that is vertically orientated that descends to ground level from a thunderstorm cloud called a cumulonimbus cloud
• what are the clouds called which tornadoes extend down to ground from?

  cumulonimbus clouds
• what is a tornado formed over water called?

  a waterspout
• do waterspouts tend to be stronger or weaker than tornadoes?

  weaker
• when do thunderstorms form?

  when warm moist air rises rapidly due to atmospheric instability
• what is atmospheric instability characterised by?

  warm moist air that is less dense near the surface with cold air above it = this makes the system want to turn over
• what creates the horizontal spin of the tornado?

  strong wind shear
• what is wind shear?

  a measure of how quickly the speed or direction of the wind changes as we go up with altitude
• where do tornadoes mostly form?

  mid-latitudes
• when is tornado season?

  from spring to early summer
• how wide are tornadoes typically?

  100 metres wide
• why is pressure lower at the centre of the tornado?

  air is rising
• where is the lowest pressure seen?

  at the centre of the tornado
• what is the typical forward speed of a tornado?

  10 - 20 miles
• how long does a tornado typically last?

  5 to 15 minutes