Geoscience Reference
In-Depth Information
The best known is the tropical cyclone that has great
potential for dramatic weather and environmental
damage, though most do not reach this level. The majority
are relatively small and intensify to give some strong winds
and precipitation but lack the warm eye of the storm.
KEY POINTS
1
Air masses are a feature of the atmospheric circulation. They develop in anticyclonic areas where air
movement is weak and acquire the characteristics of the underlying surface. As they move away from their
source area they transport these thermal characteristics. So we can refer to tropical maritime air masses
or tropical continental ones.
2
Within the main circulation flows of the westerlies and the easterlies we can find disturbances which give
rise to more unsettled weather. These have a variety of forms and names. In temperate latitudes the cyclone,
depression or low and its associated fronts are the main types of disturbance which bring rain. In tropical
latitudes the tropical cyclone is the best known feature but there are other less severe disturbances such
as easterly waves and monsoon depressions.
3
Prediction of weather-forming systems is not easy in any part of the world. For up to about ten days ahead,
mathematical and physical models of Earth's atmosphere and surface can be used to determine how the
turbulent atmosphere should change from a known starting point. Beyond that length of time the limitations
in knowledge of the original state of the atmosphere and of the models themselves give unrealistic results.
FURTHER READING
Carlson, T. N. (1991) Mid-latitude Weather Systems, London: HarperCollins. Concerned with all aspects of mid-latitude
weather systems. It includes aspects of the development of the systems as well as the weather associated with them.
Intermediate to advanced level.
McGregor, G. R., and Nieuwolt, S. (1998) Tropical Climatology, second edition, Chichester: Wiley. An updated edition
concentrating on the climatology of the tropical environment and including some general aspects of physical processes
involved. Aimed at geography and environmental science students.
WEB RESOURCES
http://www.ncdc.noaa.gov/oa/ncdc.html A
vast source of information from the US National Climate Data Center. Contains
many data sets, some of which can be downloaded together with current information about the state of the atmos-
phere in terms of ENSO and the variety of other teleconnections and hurricane activity. There is the provision of climate
information, mainly for the United States but some world maps of temperature and precipitation, etc.
http://www.metoffice.gov.uk/weather/Europe/surface_pressure.html T
he UK Met Office produce a series of surface
pressure map forecasts for up to four days ahead. Give a good idea of the nature of temperate latitude pressure systems
and their movement. Try to relate the forecast pressure patterns with the resulting weather for your area.
