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Natural Disasters > Lecture 8 > Flashcards

Lecture 8 Flashcards

1
Q

What are tropical cyclones?

A
  • these form over warm water at latitudes 5-20degrees
  • they include tropical depressions, tropical storms, and hurricanes
  • they contain high winds, heavy rain, and storm surges
  • they require a water temperature of at least 26 degrees Celsius
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2
Q

What are extratropical cyclones?

A
  • these form over land or water in temperature regions at latitudes 30-70 degrees
  • they are associated with fronts and are also called mid-latitude cyclones
  • they contain rain, snow, freezing rain, etc.
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3
Q

What is a tropical disturbance?

A

-a large area of low pressure with unsettled weather

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4
Q

What is a tropical depression?

A

-an unorganized area of thunderstorms

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5
Q

What is a tropical storm?

A

-an organized area of storms with wind of 65-119km/h

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6
Q

What is a hurricane?

A

-an area of low pressure with wind of at least 120km/h

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7
Q

What are the components of a hurricane?

A

Eye: a region in the centre with light winds and clear to partly cloudy skies

Eyewall: a ring of intense thunderstorms that whirl directly around the eye

Spiral Rain Bands: rings of tall clouds and heavy rain that exist throughout the hurricane

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8
Q

How are hurricanes named?

A
  • names were first assigned to hurricanes in 1953
  • alternating male and female names are used in alphabetical order (5 letters are skipped: Q, U, X, Y, Z)
  • the name is retired if the hurricane produced notable damage (ex: Andrew, Katrina)
  • names were exhausted for the first time ever in 2005 when 27 hurricanes occurred (final 6 that year were named after Greek letters)
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9
Q

How do hurricanes typically move?

A
  • hurricanes typically travel very slowly (less than 20km/h)
  • because wind in a hurricane rotates counter-clockwise wind speed varies over the area of the hurricane
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10
Q

How do you determine where wind speed is highest?

A

-opposing arrow will tell you the side of the hurricane with the weakest wind speeds

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11
Q

What is the most devastating component of a hurricane?

A

-eyewall

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12
Q

What is the most devastating effect of a hurricane?

A
  • it is the most devastating effect of hurricanes
  • it results from powerful winds creating an abnormal rise in sea level
  • hurricane Andrew (1992): 23ft storm surges were repeated in Florida
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13
Q

How are hurricanes classified?

A

-hurricanes are classified by the Saffir-Simpson Scale based on wind speed

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14
Q

What regions are at risk for hurricanes?

A
  • in North America areas at highest risk are found along the Atlantic coast and the Gulf of Mexico coast
  • the official hurricane season ranges from June 1st to November 30th
  • many hurricanes occur in August and early September because this is when the water is warmest
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15
Q

Describe Hurricane Juan

A
  • Sept 29 2003
  • it was a category 2 hurricane when it made landfall near Halifax
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16
Q

Describe Hurricane Hazel

A
  • Oct 15 1954
  • it killed 81 people when intense flash floods in Toronto swept away homes; no other disaster has caused that many deaths in Canada to this day
  • flooding of the Humber River caused the most damage
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17
Q

What is weather?

A
  • the state of the atmosphere at a specific time and place
  • components of weather: temperature, pressure, humidity, wind, clouds, visibility, etc.
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18
Q

What is climate?

A
  • the average state of the atmosphere over a long period of time
  • climatic averages are calculated from data over a 30 year period
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19
Q

Describe the interactions between the components of the “spheres”

A
  • atmosphere: gases
  • hydrosphere: oceans, large bodies of water
  • lithosphere: plate tectonics, orogeny
  • cryosphere: glaciers, ice sheets, snow cover
  • biosphere: vegetation, animals, humans
20
Q

Describe climate change

A
  • through Earth’s entire history (4.6 billion years), the climate has always been changing
  • over the last billion years, there have been several worldwide ice ages
  • between ice ages, the global climate was at times slightly warmer than it is today
  • the concern today is not the actual temperature; it is the rate of temperature change
21
Q

When was the last glacial period?

A
  • all of Canada was covered with ice 18000 years ago (except for Northern Yukon)
  • lower sea levels at that time exposed the Bering land bridge (between Russia and Antarctica)
22
Q

How has climate changed in recent history?

A
  • there has been a rapid rise in temperature over the past 100 years
  • this corresponds to human industry and the increase of greenhouse gases
23
Q

What are the causes of climate change?

A
  • variations in solar radiation
  • changes in composition of the atmosphere
  • changes in Earth’s surface
  • variations in Earth’s orbit
24
Q

Describe what variations exist in solar radiation

A
  • the sun tends to emit more energy during periods of high sunspot activity
  • sunspot: a cool region of high magnetism on the Sun
  • sunspots occur in cycles and reach a maximum every 11 years
  • sunspots are surrounded by faculae (bright areas that emit high amounts of energy)
  • solar output regularly changes on the order of 0.1-0.2% in relation to sunspot cycles
  • with more sunspots there is increased solar output
  • Maunder minimum (1645-1715): a time period with no sunspots; this corresponds to a time period known as the Little Ice Age
25
Q

What are changes in composition of the atmosphere?

A
  • the addition of greenhouse gases (carbon dioxide, water vapour, methane) increases global temperature
  • carbon dioxide has a long residence time in the atmosphere (100 years)
  • therefore, even if we reduce carbon dioxide today, the effects will not be felt for decades
  • a warming climate appears to be inevitable during our lifetimes
26
Q

What are ice cores?

A
  • the width of an ice layer provides insight on the temperature and snowfall of that year
  • each year, a new layer of ice forms
  • bubbles of air are trapped in the ice
  • ice cores provide climate data for up to 600 000 years in the past
27
Q

What is dendrochronology?

A
  • this is the study of tree rings
  • wider tree rings correspond to warmer or wetter years
  • tree rings provide climate data for up to 1000 years in the past
28
Q

What is the theory of plate tectonics?

A
  • the continents have moved over time
  • the collision of converging plates results in uplift and the creation of mountains
  • this affects wind, temperatures, and precipitation patterns of the surrounding landscape
29
Q

What is the Milankovitch theory?

A
  • the theory proposes that three separate phenomena relating to Earth’s orbit lead to climate change
  • they are referred to as the three Milankovitch cyles: eccentricity, precession, obliquity
30
Q

What is eccentricity?

A
  • changes in the shape of Earth’s orbit from circular to elliptical (100000 year cycle)
  • this cycle accounts for ice ages
31
Q

What is precession?

A

-the wobble of Earth’s axis (23 000 year cycle)

32
Q

What is obliquity?

A
  • changes in the tilt of Earth’s axis
  • 41 000 year cycle
33
Q

What is the greenhouse effect?

A
  • greenhouse gases allow solar radiation to pass through but they absorb infrared radiation
  • main greenhouse gases: carbon dioxide, water vapour, methane
34
Q

Describe the enhancement of the greenhouse gas effect

A
  • the greenhouse effect itself is not a concern, however the enhancement of the greenhouse effect by humans is a concern
  • adding greenhouse gases results in climate change
  • increasing the amount of carbon dioxide enhances the greenhouse effect
  • more infrared radiation from the Earth is absorbed by the atmosphere
  • carbon dioxide emissions are rapidly increasing in China and India as the economies in these countries continue to industrialize
35
Q

Describe the positive feedback of snow and ice

A
  • a process in a system that encourages the continuation of the original process
  • less snow/ice decreases the reflectivity of solar radiation (because snow is highly reflective)
  • therefore after snow/ice melts more solar radiation is absorbed rather than reflected
  • as snow and ice melt, more energy is absorbed which therefore encourages more snow and ice to melt
  • this leads to continually warmer conditions
  • it is the reason why the polar regions are warming the fastest
36
Q

What are climate models?

A
  • estimating by how much the Earth will warm is achieved by climate models
  • climate models forecast that over the next 100 years, the Earth will warm by at least 1.5 degrees
  • models solve a series of mathematical equations
  • variables represent greenhouse gases, solar radiation, other climatological components
  • to best estimate observed temperatures a climate model must incorporate many different variables
37
Q

What was the Kyoto Protocol?

A
  • a global agreement aiming to slow climate change
  • objective is to reduce greenhouse gas emissions to 5% below 1990 levels by 2010
38
Q

What are the impacts of climate change?

A
  • polar areas will warm the most
  • boreal forests will expand northward, agriculture will shift northward
  • precipitation patterns will change thus affecting habitats
  • there may be increased intensity of tropical storms and hurricanes
39
Q

What areas are at risk from sea level rise?

A
  • as sea level rises, erosion is affecting areas farther inland; some areas are eroding at 10m annually
  • sea level is projected to rise as global climate changes and ice sheets continue to melt
  • north american cities at greatest risk include Vancouver, Miami, New Orleans, and New York
  • Maldives is an island nation of 300 000 people in the Indian Ocean
  • about 80% of the country is less than 1 m above sea level
  • seawalls have been built around many of its islands to protect from waves up to 2m in height
40
Q

How does climate change impact humans?

A
  • climate change affects food production, tourism, and human health
  • the most serious impact of climate change to humans is the spread of malaria
41
Q

How does climate change impact biodiversity?

A

-warming temperatures will affect plant and animal habitats: bleaching of corals, loss of flora and fauna, extinction risk for polar bears

42
Q

How many deaths have resulted from climate change?

A
  • climate change since the mid-1970s is contributing to the cause of over 160 000 deaths per year
  • these deaths are attributed to an increase in malaria and malnutrition in less developed countries
43
Q

The recurring nature of ice ages can be explained by what?

A

milankovitch cycles

44
Q
A
45
Q
A

Natural Disasters (11 decks)

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