extreme events in climatology

Extreme Events in Climatology

Extreme Events in Climatology

HurricanesThunderstorms

TornadoesDroughts

Glaciations

HurricanesThunderstorms

TornadoesDroughts

Glaciations

Glaciations 1-30 kyrs

Extreme events in the atmosphere rival those in the geosphere They are much more mobile than events like earthquakes

affect large geographical areasand have dramatic consequences on the biosphere

severe storms or perturbations in “normal” patterns

Can cause extreme hardship on living thingsCan lead to widespread alteration of other natural systems

soil loss, increased soil development, weathering, flooding, landslides, erosion…

Extreme events in the atmosphere rival those in the geosphere They are much more mobile than events like earthquakes

affect large geographical areasand have dramatic consequences on the biosphere

severe storms or perturbations in “normal” patterns

Can cause extreme hardship on living thingsCan lead to widespread alteration of other natural systems

soil loss, increased soil development, weathering, flooding, landslides, erosion…

Tropical cyclones (Hurricanes or Typhoons)

Occur in the tropics

Are cyclones - circulation around a low pressure center

Counter clockwise rotation in Northern hemisphere driven by coriolis force

Require warm temperatures and adequate air motion to generate

Tropical cyclones (Hurricanes or Typhoons)

Occur in the tropics

Are cyclones - circulation around a low pressure center

Counter clockwise rotation in Northern hemisphere driven by coriolis force

Require warm temperatures and adequate air motion to generate

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Areas of warm water coincide with hurricane genesisAreas of warm water coincide with hurricane genesis

Warm oceans north and south of the equator spawn hurricanesWarm oceans north and south of the equator spawn hurricanes

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Hurricane paths

note the absence along the equator

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Hurricane Andrew out at sea

Hurricane Andrew approaches Florida

Hurricane categories and criteria

Single cell Multicell cluster

Multicell line Supercell

Weak to strong updrafts(non-severe)

Weak to strong updrafts (non-severe)

moderate to severe updrafts (severe)

Intensely strong to severe Mesocyclonic rotation present(severe)

Slight threat Moderate threat

Moderate threat High threat

Small areal coverage

Small-Moderate areal coverage

Moderate to large areal coverage

Thunderstorm types

Severe = <58 MPH wind, hail, and tornadoes

Non-severe = >58 MPH wind, lightning, rain

Severe = <58 MPH wind, hail, and tornadoes

Non-severe = >58 MPH wind, lightning, rain

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A single cell thunderstorm

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Multicell thunderstorms- cellularMulticell thunderstorms- cellular

Multicell thunderstorms- linearMulticell thunderstorms- linear

Squall lines and Thunderstorms

Squall lines are a line of severe thunderstorm cells, associated with a cold front.

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Direction of line movement

Direction of line movement

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Animation of a developing squall line

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Supercell development involves rotation

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Anatomy of a supercell thunderstorm

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Supercell in NSW AustraliaSupercell in NSW Australia

Tornadoes, Waterspouts, Landspouts (aka Dustdevils)

All involve rotational motion

Some waterspouts and landspouts can come from the ground (water) up

Tornadoes and some waterspouts come from the cloud down

The US leads the world in tornadoes averaging 1000 per year

Tornadoes, Waterspouts, Landspouts (aka Dustdevils)

All involve rotational motion

Some waterspouts and landspouts can come from the ground (water) up

Tornadoes and some waterspouts come from the cloud down

The US leads the world in tornadoes averaging 1000 per year

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Dust DevilsCaused by intense heating

Dust DevilsCaused by intense heating

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Droughts

By definition, a deficit in the water budget for a given region

Can be related to global circulation, regional circulation, or local conditions

Ground dries out, soil blows away, nothing grows

Example “The Dust Bowl” in the 1930’s

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Dust Bowl- ca. 1933

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Dust Bowl- ca. 1935

PDSI- Palmer Drought Severity IndexPDSI- Palmer Drought Severity Index

GlaciationDriven by Milankovitch orbital variations

Eccentricity, Obliquity and PrecessionFacilitated by feedback loops in Earth’s atmosphere and hydrosphere

oceanic and atmospheric circulation patterns change, making things colderResults in snow and ice lasting the year

Lasts 10’s of thousands of yearsa lot of retreats and advances

Last glaciation was called the Wisconsinan

occurred from 60-15 kya

GlaciationDriven by Milankovitch orbital variations

Eccentricity, Obliquity and PrecessionFacilitated by feedback loops in Earth’s atmosphere and hydrosphere

oceanic and atmospheric circulation patterns change, making things colderResults in snow and ice lasting the year

Lasts 10’s of thousands of yearsa lot of retreats and advances

Last glaciation was called the Wisconsinan

occurred from 60-15 kya

Glaciers, droughts, and tropical storm frequency all have identifiable effects on the natural world

rivers adjustsoils erode or formvegetation changeslakes form or dry up

These meteorological features are extremely sensitiveThis makes them good things to study for identifying elements of past, present and future climate change

Glaciers, droughts, and tropical storm frequency all have identifiable effects on the natural world

rivers adjustsoils erode or formvegetation changeslakes form or dry up

These meteorological features are extremely sensitiveThis makes them good things to study for identifying elements of past, present and future climate change