Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
HIGH PRESSURE High Pressure means that air tends to sink. Sinking air is compressed, warms up as a result and its relative humidity falls below saturation. Any clouds evaporate. Rainfall is unlikely, apart from occasional short, intense convectional storms due to insolation with lack of clouds in daytime. LITTLE WIND CLEAR SKIES In Britain, high pressure systems have clear skies, little or no wind, little rainfall and tend to be stable and slow moving. � Visibility is intially good, but rapidly deteriorates as dust is trapped by sinking air and is not washed out by rainfall. � Cloud cover is slight, resulting in a high diurnal ranges of temperature (hot days, cold nights). Due to the trapped dust particles and cold nights, dew, frost, fog or smog are common. � Air quality is low as all forms of pollution are retained in the lower atmosphere. � VISIBILITY IS POOR FEW CLOUDS CLEAR SKIES CAUSE FROST VISIBLITY REMAINS BETTER IN MOUNTAINS - LESS POLLUTION FOG & SMOG IS COMMON •Credit 03 How to answer …… A Weather Question How to answer …… A Weather Question Synoptic Chart for the British Isles at 0700h on 31 August A yacht race from Wick to Stornoway was due to start from Wick harbour at 8.00am on 31 August At 7.00am the Met Office advised the race organisers to cancel the race. With reference to the synoptic chart, explain why this advice was given. 5 marks What are the key words? type of boat : think! place : see map A yacht race from Wick to Stornoway was due to start from Wick harbour time : compare at 8.00am on 31 August direction : see map with map At 7.00am the Met Office advised the race organisers to cancel the race. change of plan! use the information on the map With reference to the synoptic chart, explain why this advice was given. 5 marks number of points to make Link question to the map 0700 h 31 August Where? Wick and Stornoway Direction? From Wick to Stornoway When? Race due to start at 0800h Map is for 0700h Study the map for information Occluded front: broad belt of very heavy rain, low cloud and poor visibility Cold mP air Tightly packed isobars : strong winds South westerly winds Associated weather is moving west to east Centre of low pressure : likely to bring stormy weather Warm mT air Back to the question …. Why was the race cancelled? • Competitors would risk very strong winds and • • • • therefore high seas They would be sailing straight into the wind so it would be difficult to make progress Temperatures would be low There would be heavy rain There would be thick cloud and probably poor visibility But this is not enough. Why not? “Explain.. With reference to the map” • Strong winds – close isobars • Head winds – wind direction SW • Low temperatures – mP air mass • Heavy rain – occluded front • Low cloud and poor visibility – occluded front 5 marks Study the synoptic chart below and describe the likely weather conditions in Glasgow (G) and Lyon (L) Miss Anything? remember to include wind, rain and temperature. What type of air pressure are they experiencing? Look at the spacing of the isobars. • Glasgow will be experiencing periods of heavy rain with a short dry period in between. The winds will be high. • Lyon will be experiencing dry, sunny weather with clear calm skies. There will be low temperatures and possibly frost. Other topics to revise • Air masses • Weather instruments • Station circles • HP and LP Each of 4 zones has issues: • Deforestation in the RAINFOREST • Desertification in the DESERT • Oil development in the TUNDRA • Tourism in the Mediterranean and ocean pollution. • LOOK over notes and check • http://www.scalloway.org.uk/phye1.htm