Weather forecasting

EG1204 Earth Systems

Dr Jonathan Lageard

Weather

• ‘Overall state of the atmosphere on a time-scale of minutes to months’ Thomas & Goudie, 2000 p527

• Weather describes specific conditions rain, temperatures, dew-point, wind speed and direction, visibility…

Weather forecasting• ‘The science of predicting the future state of the

atmosphere from very short periods of less than one hour up to 7-10 days ahead’ Thomas & Goudie, 2000 p527

• Climatic regions / climate graphs

• Mid-latitude weather (UK)

• Weather monitoring / forecasting

• Weather & climate practical

content

Global temperature patterns (Jan) Barry & Chorley 2003 p43

Global rainfall patterns Holden, 2005 p39

Holden 2005, p30

Hadley cell regime Thompson 1998, p

Source Flohn 1957 in Barry & Chorley, 1996 p340

Cool Antarctica, 2007

Climate graphs

Landes-Pyrenees Properties, 2007

London climate graph

Weather maps

Air Ministry 1941. The Weather Map. London, HMSO

Stirling, 1997 p25

Synoptic weather chart, Met Office 2000

Stirling, 1997 p28

Weather systems

Air masses: Source regions

Fronts

JetstreamsAerospace Technology, 2007

Mid-latitude weather (UK)

Model of N hemisphere atmospheric circulation Thompson 1998 p107 based on Hanwell 1980

Depressions (cyclonic systems)

a) cross-sectional model

STAGES:

Embryo: Tm & Pm air mix warm air less dense rises in spiral Low Pressure

Mature: Pressure falls warm air rises in warm sector winds inward blowing anticlockwise Coriolis force

Decay: Cold front catches warm front = Occlusion

b) plan form / synoptic chart

What does a depression look like?

Met Office, 2007

Weather associated with the passage of a depression

Waugh 1995, p215Cloud patterns associated with a depression Thompson, 1998 p151

Depression tracks (courses) Stirling, 1997 p30

North Sea storm surge 31st January to 1st February 1953

Impacts:

coastal areas UK, Belgium & Netherlands

Economic damage and community disruption

2,000+ people died across the three countries.

Jonkman SN & Kelman I, 2005

Anticylcones

Large masses of subsiding warm dry air (settled weather)

winds outward-blowing, clockwise

Associated weather

Summer: hot days (heatwave), rapidly cooling night, land-sea breezes, temperature inversions

Winter: similar, but cold / snow, fog / frost

Stirling, 1997 p28

Weather system terminology

Musk, 1988

Weather forecasting: tools / data

Met Office, 2007

Met station, Muckross House, Killarney NP

Instruments: Met Office, 2007

Met Office, 2007

Satellite images

http://www.metoffice.co.uk/

Met Office, 2007

UK observations regional map (Met Office, 2007)

Met Office, 2007

Met Office, 2007

‘We interrupt TMS to bring you the following gale warning issued by the Met office at 17.25 GMT Wedesday 14th March…’

Directed reading:

• Mountain weather / local climates – Holden 2005 pp80-96

• UK weather system variants Met Office 2007 – Learning – Weather resources – Higher - weather systems

• Hurricanes (storm of 1987 – Met Office, 2007, Barry & Chorley 2003 pp269-275)

Suggested reading

• Barry RG & Chorley RJ 2003. Atmosphere, Weather and Climate (8th Edition). London, Routledge.

• Earth Science and Geography, Keele University 2007. The Weather at Keele (Keele Weather station).

http://www.esci.keele.ac.uk/weather/ (accessed 13.3.07)• Holden J (Ed) 2005. An Introduction to Physical Geography and the

Environment. Harlow, Pearson. (Atmospheric processes, global climates, local & regional climates pp27-96).

• Met Office 2007. Met Office homepage. http://www.metoffice.gov.uk/index.html (accessed 12.3.07) Folllow links to Learning – Weather resources - Higher

• O’Hare G, Sweeney J & Wilby R 2005. Weather, Climate and Climate Change. Harlow, Pearson.

• Stirling R 1997. The Weather of Britain. Routledge.• Thomas DSG and Goudie A 2000. The Dictionary of Physical

Geography. Oxford, Blackwell. • Thompson RD 1998. Atmospheric Processes and Systems.

London, Routledge.