Climate Variation and Drought

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24 Terms

1

what is the walker circulation?

  • an atmos circulation in the equatorial regions of the pacific ocean

  • warmer water in the western Pacific → causing pow-p, warmer air

  • cooler ocean water in the east pacific → causing high-p, cooler air

  • winds blow surface ocean water westward (increase sea lvl). cool deep ocean water wells-up along the west coast of South america bringing deep, nutrient-rich seawater to the surface, allowing fish pop to thrive

<ul><li><p>an atmos circulation in the equatorial regions of the pacific ocean</p></li><li><p>warmer water in the western Pacific → causing pow-p, warmer air</p></li><li><p>cooler ocean water in the east pacific → causing high-p, cooler air</p></li><li><p>winds blow surface ocean water westward (increase sea lvl). cool deep ocean water wells-up along the west coast of South america bringing deep, nutrient-rich seawater to the surface, allowing fish pop to thrive</p></li></ul>
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2

what is la Nina?

  • more amplified ‘normal’ condition leading to direr and cooler conditions in south america and more rainfall in indonesia

<ul><li><p>more amplified ‘normal’ condition leading to direr and cooler conditions in south america and more rainfall in indonesia</p></li></ul>
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3

what is el nino?

  • occurs when surface winds weaken

    • tilted sea surface flattens n warm pacific water flows to the eat → water flows back to equilibrium

    • water on coast of south america become nutrient poor and impacts fish pop

    • droughts occur in australia/indonesia while storms n flooding occur on the coast of the americas

<ul><li><p>occurs when surface winds weaken</p><ul><li><p>tilted sea surface flattens n warm pacific water flows to the eat → water flows back to equilibrium</p></li><li><p>water on coast of south america become nutrient poor and impacts fish pop</p></li><li><p>droughts occur in australia/indonesia while storms n flooding occur on the coast of the americas</p></li></ul></li></ul>
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4

Enso conditions

  • ENSO = el nino/southern oscillation

  • sea surface temperature anomalies in the mid-pacific ocean for 1900-2003

  • el nino has warm temperature anomalies

<ul><li><p>ENSO = el nino/southern oscillation</p></li><li><p>sea surface temperature anomalies in the mid-pacific ocean for 1900-2003</p></li><li><p>el nino has warm temperature anomalies</p></li></ul>
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5

global impact el nina/nino

knowt flashcard image
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6

what are monsoon?

  • seasonally changing air circulation in the world’s tropical n subtropical regions in which summer winds blow from the ocean toward the land, bringing heavy rain inland

    • in summer, land heats faster than ocean; most ocean flows inland

  • in winter, winter winds blow from the land toward the ocean, causing drier weather inland

    • land cools faster than ocean; air flows toward ocean

  • winter n summer r opp

<ul><li><p>seasonally changing air circulation in the world’s tropical n subtropical regions in which summer winds blow from the ocean toward the land, bringing heavy rain inland</p><ul><li><p>in summer, land heats faster than ocean; most ocean flows inland</p></li></ul></li><li><p>in winter, winter winds blow from the land toward the ocean, causing drier weather inland</p><ul><li><p>land cools faster than ocean; air flows toward ocean</p></li></ul></li><li><p>winter n summer r opp</p></li></ul>
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7

monsoons in south asia

  • normally bring 2 months of flooding

  • agriculture depends on regular monsoon rain

  • economic disaster occurs when monsoon rains fail

  • droughts occur if rains do not arrive → no crops = no feeding

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8

what is drought?

  • a deficiency of freshwater within a region lasting long enough to harm normal vegetation, crops, livestock, surface n underground water supplies, human health, and human activities

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9

Dust bowl

  • decade long drought in the 1930s led to severe drought

  • soil has no vegetation, so lifted into clouds

  • dust storms carried away topsoil

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10

what are the 3 types of drought?

  • meteorological drought

  • agricultural drought

  • hydrological drought

    → they r sequential

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11

what is a meteorological drought?

  • precipitation is less than normal for weeks or yrs

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12

what is agricultural drought?

  • low soil moisture

  • inhibits crop germination or growth

  • may be caused by human activity

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13

what is hydrological drought?

  • insufficient water flows into lakes, streams, or reservoirs

  • surface-water lvl drop

  • water table drops

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14

drought positive feedback

  • hot, dry weather increases evaporation, causing ground to dry out

  • dry ground contributes to less moisture to air

  • plants die, contributes less moisture (evaporation) to air and less shade on the ground

<ul><li><p>hot, dry weather increases evaporation, causing ground to dry out</p></li><li><p>dry ground contributes to less moisture to air</p></li><li><p>plants die, contributes less moisture (evaporation) to air and less shade on the ground</p></li></ul>
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15

what does the palmer drought index measure?

  • moisture deficiency, relative to avg conditions

  • compares 2 variables:

    • water supply from precipitation n reserves

    • water depletion from evaporation, infiltration, n runoff

  • allows scientists to visualize cumulative changes over time

<ul><li><p>moisture deficiency, relative to avg conditions</p></li><li><p>compares 2 variables:</p><ul><li><p>water supply from precipitation n reserves</p></li><li><p>water depletion from evaporation, infiltration, n runoff</p></li></ul></li><li><p>allows scientists to visualize cumulative changes over time</p></li></ul>
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16

what are droughts in cali caused by?

  • insufficient snow in Sierra Nevada created low water supplies

<ul><li><p>insufficient snow in Sierra Nevada created low water supplies</p></li></ul>
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17

when was cali’s worst drought in 1,200 yrs?

  • 2011-2017

    • devasted crops

    • inconvenienced millions of peep

    • killed millions of trees

  • reservoirs dropped to all-time low lvls

<ul><li><p>2011-2017</p><ul><li><p>devasted crops</p></li><li><p>inconvenienced millions of peep</p></li><li><p>killed millions of trees</p></li></ul></li><li><p>reservoirs dropped to all-time low lvls</p></li></ul>
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18

what does monsoonal climate have?

  • have wet n dry seasons

  • heavy rain falls during wet season

  • little/no rain falls during dry season

→ risk of famine

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19

when do droughts occur?

  • if rain f n intensity drop

    • reservoirs n streams rapidly dry out

    • crops n livestocks die as soil dries

  • densely pop areas r at high risk of famine

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20

in a monsoonal climate zone, the shift from drought conditions to flood conditions can happen ____________

  • rapidly

→ shown by precipitation records from east-central africa and madagascar

<ul><li><p>rapidly</p></li></ul><p>→ shown by precipitation records from east-central africa and madagascar</p>
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21

droughts in africa

  • poor dev n poverty increases drought risk in africa

  • horn of africa has been n a drought since 2011

  • 17 million peep face water stress n food insecurity

  • 5.5 million peep have access to only contaminated water

  • lack of infrastruct n poor security hamper relief efforts

<ul><li><p>poor dev n poverty increases drought risk in africa</p></li><li><p>horn of africa has been n a drought since 2011</p></li><li><p>17 million peep face water stress n food insecurity</p></li><li><p>5.5 million peep have access to only contaminated water</p></li><li><p>lack of infrastruct n poor security hamper relief efforts</p></li></ul>
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22

drought effect on lake chad

  • hydrological drought has led to the progressive shrinkage of lake chad, central africa

  • formerly the world's 6th largest lake

  • lake chad has decreased by 90% due to climate change, pop growth n irrigation

<ul><li><p>hydrological drought has led to the progressive shrinkage of lake chad, central africa</p></li><li><p>formerly the world&apos;s 6th largest lake</p></li><li><p>lake chad has decreased by 90% due to climate change, pop growth n irrigation</p></li></ul>
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23

video

  • el nino effect

  • lack of rain + sever drought

  • cow death (livestock in general)

  • poor government intervention

  • food security at risk

  • people starving to death

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24

what are the impacts of drought?

  • severe natural hazard in many areas of the world often accompanied by famine n starvation

  • often called a ‘creeping’ phenomena until conditions have deteriorated

  • costs r more difficult to assess than other hazards

    • China, 1928: 3 million deaths

    • NE Africa, 1983:150,000 deaths

    • Somalia, 2017–2018: Food shortages for 6 \n million

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