hurricanes! Flashcards
the eye of a hurricane has what kind of air pressure?
low!
earths motion in the northern hemisphere is?
clockwise!
how are tropical cyclones formed?
really low air pressure, water evaporates, cools off, change in energy carried by vapor, condenses into energy, carries up, and starts again
what are the categories for hurricanes?
5 is strongest, one is weakest
how many subtropical storm hits every other year in canada?
one
how many storms in canada may develop into a hurricane?
some
what was one of the deadliest hurricanes to impact canada?
hazel
what was one of the most powerfull hurricanes to ever make landfall in canada?
juan
why worry about coastal processes?
population is selectively living close to coastlines, which puts people more at risk
on average, population increasing, density increasing, and more of these people are choosing to live near the coast
more people want to live 0-5km from coastline
what are factors that impact coastlines?
tectonic setting
materials present at the shore
energy of water striking coast
what are the two categories of coastlines?
-land itself is rising from plate tectonics
-land itself is standing still
what are the two margins?
active margin: associated with active plate (BC); mountainous
passive margin: far from active plate tectonics (pei, newfoundland); very flat!
what are the signs of changing relative sea level?
wave-cut platform: form at coastlines
drowned valley
how does slope affect flooding?
higher slope = less impact
lower slope = more impact
what is a submergent coastline?
simple stream where land underneath it is sinking
what is an emergent coastline
steps on the coastline that can be recognized
what are the primary forces regulating natural shorline modification
waves and currents
waves are induced by?
wind passes over water, wind drags on water surface, creates wave
faster wind, bigger space, bigger waves
what is the wave base?
given size of wave on the surface, how deep does the energy go down?
with waves, energy is carried, but water molecules?
stay put
how are breakers formed
wave travels, water same place, bottom shallows to 1/2 wavelength, wave slows, length decreases, crest sharpens, at shore they are too step, break
wave energy is approximately proportional to?
the square of wave height!
- wave increases 2m, the wave energy increases by 4
what causes tides?
the gravitational pull of the sun and moon on the bulges in the oceans water mass
what is a tidal flat?
exposed area after ebb tide moves out
how do tides flow?
tide rise, water flows toward shore (flood tide), tide passes high stage and falls, ebb tide move out, tidal flat exposed
what are longshore currents?
lateral component of wave motion, govern aspects of sand deposition occurring on beach shorelines
what is littoral drift
waves at angle, sand grain moves along the shoreline in response
what are the inputs of sand budgets on a beach?
- sediment erodes from backshore cliffs by waves
- sediments eroded from up-current beach by longshore drift and current
- sediment brought in by rivers
what are the outputs of sand budgets on a beach
sediment transported to backshore dunes by offshore winds
sediments transported down-current by longshore drift and current
sediments transported to deep water by tidal currents and waves
what are some artificial barriers to stabilize beaches from coastal erosion?
breakwaters
jetties
groins
what is a storm surge?
an abnormal rise of water generated by a storm, over and above the predicted tides
the impact on surge from water being forced between the shore by wind is
extreme
how are tsunamis created
large earthquakes below or near ocean floor
transfer all energy towards shoreline, like a hurricane
what was one of the tsunami impact sites?
chicxulub asteroid impact near yutcatan peninsuala produced by a global tsunami
first 15-20 minutes after impact, creating wave at least 10m high
what is believed to happen to sea level in atlantic canada? what about coastal erosion?
sea level continue to rise
coastal erosion will increase dramatically as sea level rises
what is the effect of sea level rise on the risk of flooding?
-climate warming leads to sea level rise that will exacerbate (increase) hurricane damage
-calculation is only based on only sea level rise, not change in storm intensity nor frequency
-what used to happen every 100 years is now going to happen every 65 years as sea level rises
number of storms is ____ going to change, but the intensity, the season they occur, and the trjactory of the storms _____
not; will
