Learn more about this course. A passing depression xx. Come Rain or Shine 19 Aug, Too centred on England close Europe to be of any help or interest to those living Down Under. Visit the course. Everything was clear and precise 06 Jul, I wish to suggest that on the synoptic charts the outline of countries be slightly bolder than the pressure contour Very interesting.
Thank you for teaching us 28 Jun, Come Rain or Shine 09 Jun, Professor Innes has a great teaching style one I have learned 19 Aug, If you are interested in meteorology, weather and climate this course is tailored just Good educational tool 27 Jun, Great overall introduction to the big picture.
Looking forward to the follow-up course. If a depression were passing over you, when would you expect there to be cloud, what sort of cloud would you see, and when would it rain? Think about standing near the right hand edge of the diagram above. As the system approaches you from the west, the first thing that reaches you is the warm front, far above your head.
The result is steady rain, later giving way to drizzle and finally clearer skies with high cirrus clouds. Behind the warm front is an area of warm, rising air and low pressure - the centre of the low-pressure system.
As this part of the depression passes over, there may be a short period of clear, dry weather. As the rapidly rising warm air cools, its water condenses and clouds form cumulonimbus, then cumulus. The result is heavy rain or thunderstorms, giving way to showers and finally to clear skies as the cold front moves away eastwards.
A depression on a weather chart Key features of a depression Pressure — Low and falling below mb. Temperature — Varies depending on the air mass passing overhead and the time of year. Cloud cover — An ever-changing selection of clouds will change as the depression passes. The maximum amount of cloud will be when the cold front passes overhead. Wind speed and direction — Strong winds will usually blow in an anticlockwise direction.
Much of the public transport in the capital was not functioning, and people were advised against trying to go to work. The MetOffice were critised including Michael Fish, but the lack of a weather ship in the Southwest Approaches, due to Met Office cutbacks meant the only manner of tracking the storm was by using satellite data, as automatic buoys had not been deployed at the time.
The climate of the British Isles Origin and nature of depressions. Weather changes associated with the passage of a depression. The sequence of formation for mid latitude depressions is as follows; Warm air Tropical maritime migrating north from the tropics meets cold dense air Polar Maritime migrating south from the Polar region.
This is as a result of the global pattern of atmospheric circulation set up by imbalances in the global heat budget. At both fronts air is rising, so it cools initially at the Dry Adiabatic Lapse rate 9.
The cloud types at the 2 fronts are different however. Cirrus, cumulus and Nimbo stratus are common on the warm front where warm air is slowly lifted over the cold air in front of it. This gives prolonged but lighter rainfall. Behind the warm front, Cumulonimbus and stratus clouds form at the trailing cold front, as the uplift of warm here is more rapid. This means that the second band of cloud brings shorter but more intense bouts of precipitation.
Note that this is a cross section through the depression. As this storm passes from the West to the East it drastically changes the weather based upon the processes of formation outlined above. This weather changes over time, as the storm progresses on its regular journey from South West to North East.
The Warm front is associated with the more gentle uplift of warm tropical air above the colder polar air. Therefore as the warm front passes over the British Isles places will tend to have falling pressures, winds that are picking up in strength, high and thinner clouds such as Cirrus and Cirrostratus giving way to lower altostratus and nimbo stratus, and a slow rise in humidity and rainfall levels.
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