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IntroductionBasic dynamics
Anatomy of a stormForecasts
The Jet Stream, high and low pressure systemsand fronts; Understanding the weather
Joe LaCasceDept. of Geosciences
January 25, 2010
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Table of contents
1 Introduction
2 Basic dynamicsGeostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
3 Anatomy of a stormStorm formationFronts
4 Forecasts
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Hurricane
Figure: Hurricane Ivan, Sept. 2004
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Polar low
Figure: A polar low over the Barents Sea, 27 Feb., 1987
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Hurricane
Figure: Hurricane Katrina, Aug. 2005
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Flooding
Figure: Coastal flooding, England
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Snow
Figure: Chicago, 2009
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
8 Jan., 2010; www.yr.no
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
8 Jan., 2010; www.yr.no
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
Dynamics
Basic balances:
Geostrophic balance
Hydrostatic balance
Thermal wind balance
Phenomena:
Pressure systems
Jet Stream
Fronts and precipitation
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
Rotation
veltotal = velperson + velrotation
so:velperson = veltotal − velrotation
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
Deflection
Figure: Deflection to the right in the Northern Hemisphere
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
Low pressure without rotation
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
Low pressure with rotation
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
High pressure with rotation
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
Geostrophic balance
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
Hurricane
Figure: Hurricane Ivan
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
Hydrostatic balance
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
Thermal wind
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
Jet stream
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
Jet stream
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
Jet stream
Figure: Wallace and Hobbs, 2006
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Geostrophic balanceHydrostatic balanceThermal wind balanceThe Jet Stream
Instability and turbulence
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Storm formationFronts
Jet stream
Figure: Wallace and Hobbs, 2006
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Storm formationFronts
Storm formation
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Storm formationFronts
Storm formation
Figure: Wallace and Hobbs, 2006
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Storm formationFronts
Fronts
Warm/cold fronts
Vertical motion
→ precipitation
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
Storm formationFronts
Squall
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
8 Jan., 2010; www.yr.no
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
8 Jan., 2010; UK Met Office
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
9 Jan., 2010; UK Met Office
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather
IntroductionBasic dynamics
Anatomy of a stormForecasts
25 Jan., 2010; UK Met Office
Joe LaCasce Dept. of Geosciences The Jet Stream, high and low pressure systems and fronts; Understanding the weather