Be wary of the main storm hazards.
Lightning, tornado, hail, downpours of rain,
downpours of gust; hurricanes: contain thunderstorms, coastal erosion, storm surge,
coastal flooding, and high waves.
Describe the different types of lightning, how they form, and what happens when they
Cloud to cloud lightning: occur when the voltage gradient within a
cloud or between clouds overcomes the electrical resistance of the air. Cloud to ground:
Charge separation occurs, with positive and negative charges separate in the cloud.
Charge separation occurs only in clouds are above the freezing level. Runaway discharge
theory: electrons get sped up to near the speed of light, when they are this fast, resistance
is decreased and they go faster, collide with atoms and get more electrons. Strikes can be
negative or positive, positive less common and come from the anvil. Biggest risk in
Ontario, distance away = seconds / 3. Stepped leader advances is not a single column,
create a zig zag shape, when it approaches the ground, spark from ground connects with
it, and a pathway of strokes, or return strokes flow down. Then another leader comes
down called a dart leader. Types of lightning: ball lightning, St. Elmo’s fire: tall objects
glow as they emit sparks, makes air blue. Sprites: electrical burts that rise from cloud
tops. Blue jets: upward moving electrical ejections from the tops of thunderstorms.
Recognize thunderstorms, be able to identify Tstorm components, and and explain how
Components: anvil, top of tstorm, can be 100km in diameter, can have
overshooting dome if very strong updrafts, main updraft: 15 km diameter, flanking line
following behind, striations: (spinning). Underneath: funnel cloud or tornado, rain in
front of cloud. Large cells that evolve 15-30 mins, usually more than one cell, multicell
3 stages, cumulus, mature, and dissipative. Cumulus: unstable air raises, brings
water vapour from surface to troposphere, it becomes humid enough that clouds begin
undergoing vertical growth at 5 – 20m/s, the temp decreases cloud extends above
freezing level. Mature: precipitation begins to fall, downdrafts form where precipitation
is highest, most powerful part of storm, updrafts dominate interior of cloud, downdrafts
are outside. Dissipative stage: downdrafts occupy more of the base, and supply of water
vapor is cut off, precipitation diminishes and water evaporates
Explain how storms get their energy from the sun.
Sun releases energy into atmosphere,
some is absorbed into the ground, some is reflected into space, some into clouds, some
released as latent and sensible heat. Latent heat increases humidity, sensible heat
increases temperature, storms need both to be created. Highest time of thunderstorm
likelihood is late afternoon early evening.