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Sources: BBC, National Weather Services, Intellicast, Space Science and Engineering Center, the Met Office, Yahoo! Weather
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TODAY’S HEADLINES
SAD NEWS
The Principal (headmaster) of a MetLink school suffered two heart attacks last Sunday and passed away on Tuesday night. Please remember the teachers and students of Howell Middle School, Victoria, Texas, USA. We send our most sincere condolences to them all and to the Principal’s family.
NEW YESTERDAY:
EL NIÑO
The important and far-reaching ocean-atmosphere phenomenon called El Niño has been developing in recent weeks. Click here (a) to read about the developments and their possible consequences (b) to find links to sites that provide detailed information about El Niño.
TODAY’S
EXTREMES
Hottest: The International Community School, Addis Ababa, Ethiopia, 35°C
Coldest: Vasa övningsskola, Finland, -13.1°C
Windiest: Queen’s Park Community Technology College, Blackburn, Lancashire, UK; Delabole Community Primary School, Cornwall, UK; both Force 8
Wettest: Penryn College, Mpumalanga, South Africa, 13 mm
TODAY’S REVIEW OF METLINK
OBSERVATIONS
Have you looked at today’s weathercams? If not, click here.
To view today’s observations in the database, click here.
To find out how your observations compare with the average for March, click here.
NB: It is early spring in the northern hemisphere, early autumn in the southern.
A feature of the weather in the MetLink world this week has been the lack of heavy rain. Where rain has fallen, amounts have generally been quite small (less than 10 mm), and many places have been dry and sunny. Another feature has been that most places in the MetLink world have been warmer than average for the time of year.
AUSTRALIA, NEW ZEALAND, INDIA AND INDONESIA
"Another beautiful day in North Otago", wrote the students of Pembroke School, Oamaru, New Zealand. Temperature 17.0°C at 10 am Local Time (21:00 GMT on 13 March). Cloud amount two oktas (of stratocumulus); wind from the west 9 km/h. Maximum temperature 20.3°C, minimum 8.0°C. "A beautiful sunny day", too, at Woodbridge, Tasmania, where, at 2.35 pm Local Time (03:35 GMT), the temperature was 20.5°C and the cloud amount only 3 oktas (of cumulus). Calm and sunny at Donald High School in Victoria at 2.30 pm Local Time (03:30 GMT). Just one okta of cloud (cirrus and altocumulus) and the temperature 27°C. Relative humidity only 33%. Maximum temperature 31.0°C, minimum 10.5°C. Similar at Millmerran in Queensland, where, at 11.13 am Local Time (01:13 GMT), the temperature was 24.3°C and the relative humidity only 41%. Cloud amount only one okta (cumulus) and the wind from the south-east, 9 km/h.
Two observations today from Greenwood Senior High School in Western Australia. One at 10.45 pm Local Time (14:45 GMT), the other at 11.35 pm. Temperature 25.0°C at the earlier time, 28.6°C at 11.35. Maximum temperature 30.5°C. Rain expected but did not materialise. "Water restrictions apply", the students reported. They also noted: "maximum at coastal school was seven degrees lower than at the airport 37.5°C".
"Hot and sunny" in Singapore, where, at 2.30 pm Local Time (06:30 GMT), the temperature was 33.0°C and the wind Force 1 (from the north-east). A "nice day" at Jakarta, where, the temperature was 23.5°C at 7 am Local Time (00:00 GMT). Calm with only one okta of cloud (cirrus). Maximum temperature 31.0°C, minimum 23°C.
Smoke haze reported from Medan, Sumatra, Indonesia. "Some people are comparing it with 1997", the school’s contact reported. "It certainly affects our temperatures. We haven’t had any rain for a fortnight* and, apparently, this is what we need to get rid of the haze. It’s like being in a fine, smelly mist all the time. There are some 350 major fires in the region, many of them deliberately lit by loggers and plantation workers". (* a fortnight is a period of two weeks)
The day was sunny, too, at The Assam Valley School in India, where, at 2 pm Local Time (08:30 GMT), the temperature was 32°C and the wind a very gentle south-westerly Force 1. Just a few cumulus clouds in the sky. Maximum temperature 34°C, minimum 21°C.
AFRICA AND ASCENSION
The weather was cloudy and warm with some rain on Ascension Island, the clouds being cumulus and cumulonimbus. Temperature 27°C at 12.45 pm Local Time (12:45 GMT). Wind 9 km/h from the north-east. Maximum temperature 33°C, minimum 24°C. Another place where rain fell today was Marondera in Zimbabwe, the first rain in two months. Temperature at 8 am Local Time (06:00 GMT) 22.8°C. Maximum temperature 26.9°C, minimum 20.4°C. Rain, too, and humid in Bulawayo, Zimbabwe. Slight rain falling at 7.30 am Local Time (05:30 GMT). Calm with 6 oktas of cumulus and stratocumulus cloud. Temperature 19°C. Relative humidity 91%. Maximum temperature 31°C, minimum 19°C. No rain at Kgaswe in Botswana, though. Sky cloudless. No wind. Temperature at 8 am Local Time (06:00 GMT) 20°C. Maximum temperature 26°C, minimum 19°C.
"A beautiful morning" at Highbury Preparatory School in KwaZulu Natal, South Africa. No wind, no cloud. "Birds singing", the students reported. Temperature at 7 am Local Time (05:00 GMT) 19°C. maximum temperature 24°C, minimum 18°C. "We need rain badly", the Highbury students reported at 1 pm Local Time. Temperature then 26°C. Wind 9 km/h from the south-east. Cloud 3 oktas of cumulus.
Dry at Port Elizabeth, too. Cloudless at 1 pm Local Time (11:00 GMT) with a temperature of 25°C. Maximum temperature 29°C, minimum 15°C. Rain at Penryn College in Mpumalanga, though. Rain of medium intensity reported at 1 pm Local Time (11:00 GMT). Temperature 25°C.
"No let up in the humid and clammy conditions", said the students of Grantleigh College, KwaZulu Natal. Temperature 28.8°C at 11 am Local Time (09:00 GMT). No rain, though. Maximum temperature 31.7°C, minimum 25.5°C. "Oh dear, end of summer" was today’s report from Micklefield School, Cape Town. Drizzle falling at 10.30 am Local Time (08:30 GMT) and 7 mm of precipitation measured. Temperature 24°C. Wind 44 km/h from the north-west and the cloud amount 7 oktas of stratocumulus. Foggy this morning at Greenside High School, Gauteng, but a "moderately warm and mild day" followed. Temperature 27°C at 2.30 pm Local Time (12:30 GMT) and the cloud amount 5 oktas (of cumulus, stratocumulus and nimbostratus). Calm. Maximum temperature 27°C, minimum 12°C.
Sunny and warm at Addis Ababa. Temperature 20.0°C at 11 am Local Time (08:00 GMT). One okta of cirrus cloud and a light northerly breeze (9 km/h). Relative humidity only 45%. Maximum temperature 35°C, minimum 18.0°C.
EUROPE
Warm and sunny in Constanta, Romania. Light winds and small amounts of cirrus cloud. "A very wonderful day of spring", the students reported. Temperature up to 13.8°C, which is considerably above average for the time of year. Temperature about the same in Milan, 12°C at 11.20 am Local Time (10:20 GMT) and also sunny (3 oktas of stratus cloud). Not so pleasant in Spain, though. Rain of medium intensity reported from Tarragona, and rain in Madrid, too. Temperature at Tarragona 13.1°C at 10.10 am Local Time (09:10 GMT), the wind from the south-west, 9 km/h. Maximum temperature 16.0°C, minimum 8.0°C. Cooler on the Spanish plateau. Temperature at Madrid 9°C at 3.15 pm Local Time (14.15 GMT). Maximum temperature 10°C, minimum 6°C.
"A cool clear day" in Aalborg, Denmark. Only one okta of cirrus cloud at 12.10 pm Local Time (11:10 GMT) and the wind Force 1 from the north-east. Temperature 4°C. Maximum temperature 7°C, minimum +1°C. Not so pleasant in Luxembourg, though, with slight drizzle and 8 oktas of stratus cloud at 11.45 am Local Time (10:45 GMT). Temperature 8°C and the wind Force 1 from the north. Considerably cooler than of late in Strasbourg, where the temperature was 6°C at 8.30 am Local Time (07:30 GMT), 8°C at 1 pm and 5.30 pm. Maximum temperature 21°C! Slight drizzle falling at 1 pm, rain of medium intensity at 5.30 pm.
Breezy and cool but cloudless in Aizpute, Latvia. Wind from the north-east 24 km/h at 12.30 pm Local Time (10:30 GMT) and the temperature then +1.2°C. Maximum temperature 1.2°C, minimum —2.2°C. Sunny but cold, too, at Bor School in Sweden, where the temperature at 8 am Local Time (07:00 GMT) was —3.7°C. Wind only Force 1, though, from the south-east. Maximum temperature 5.8°C, minimum —4.2°C. Another place that was sunny was Mikkeli, where it was a "beautiful glittering winter day". Temperature —3.0°C at 12 noon Local Time (10:30 GMT). Wind from the west Force 1. Maximum temperature +0.6°C, minimum -12.0°C. "Nice winter weather" at Vasa, where there was only one okta of cirrus cloud at 3.35 pm Local Time (13:35 GMT) and the wind was a very light south-westerly. Temperature then +0.8°C. Maximum temperature 5.9°C, minimum —13.1°C. "Quite chilly but sunny and clear" at Oslo, where the temperature was —0.5°C at 12.20 pm Local Time (11:20 GMT) and the wind a light (9 km/h) southerly. Maximum temperature 10.0°C, minimum -8.9°C.
Wintry in southern England, with a fresh to strong easterly wind and temperatures several degrees below average for the time of year. Rain and sleet (snow-rain mixture) fell in many parts of southern England this afternoon and evening. Temperature in Reading, the home of the Royal Meteorological Society, 6°C at 9.15 am but only 4°C at 3 pm. Wind speeds over 30 km/h almost everywhere in southern England and South Wales. "A very windy cold day" at Coed Cae Junior School, in south-east Wales. Very cold and lightning seen at Delabole in Cornwall. "Very high winds for the last 17 hours", the students reported. Maximum temperature only 7°C at Truro in Cornwall. "A wet and cold day with a bitterly cold wind" at the Dragon School, Oxford. "Cold and windy" at Pinewood School near Swindon. "A very cold easterly wind" at Radley College, near Oxford. "Cold, windy, dull and cloudy" at Chaldon Primary School in Surrey. Slight rain and a temperature of 4°C at 9 am at Cottesmore School, West Sussex. "Very chilly with temperatures very low for the time of year" at the Royal Hospital School in Suffolk. "Definitely still winter", said the students of Lindfield Primary School in West Sussex. "A gnawing east wind" and slight drizzle falling.
Cold almost everywhere in the British Isles but sunny in many places away from the cloudy south. "Windy and cold" but only 2 oktas of cloud over Dublin at 10 am. Temperature then 7°C. "Sunny, cold and breezy" at St Theresa’s National School in Galway at 10.30 am, when the wind was from the south-east 33 km/h and the cloud amount 2 oktas (of cirrus). Temperature, as in Dublin, 7°C. "A cold windy day making ears sting and trees sway" at St Patrick’s Primary School in Lancashire and "blustery feels cold" at St Oswald’s Primary School in Sheffield. "Sunny and windy" at Honeybourne First School in Worcestershire. Only 3 oktas of cloud (altocumulus and stratocumulus) at Beaconhurst School near Stirling at 9.45 am and the wind there very light (Force 1). "A sunny spring morning with a light breeze" at Farr High School, on the north coast of Scotland. A light wind (Force 1) at Paible School on North Uist, too.
NORTH AND SOUTH AMERICA
Slight rain at Punta Arenas this morning. Wind from the east: 44 km/h at 11 am Local Time (15:00 GMT), 24 km/h at 2 pm Local Time. Temperature only 5.1°C at 2 pm. Sky completely overcast at 11 am, 6 oktas of altostratus at 2 pm. Maximum temperature 5.9°C, minimum 4.2°C.
"A cloudy cool day" at Aurora, Illinois. "The sky looks unhappy and almost ready to cry". Sky completely overcast with stratus cloud. Wind 15 km/h from the south-east. Temperature 12°C at 11 am Local Time (17:00 GMT). Maximum temperature 12°C, minimum 4°C. Not a very nice day at Victoria, Texas, either. Slight drizzle from 8 oktas of nimbostratus and stratocumulus cloud at12.50 pm Local Time (18:50 GMT). Wind 33 km/h (from the south-west). "A very humid windy day", the students reported. "Muggy even in the classroom". Temperature at 12.50 pm 22°C, relative humidity 83%. Maximum temperature 27.5°C, minimum 17°C.
Sunny but windy at Reseda in California. "The wind is blowing strongly and coldly", the students reported. Cloud amount 2 oktas of cumulus at 11.04 am Local Time (19:04 GMT). Wind 44 km/h from the north-west. Temperature 12.4°C, relative humidity only 38%. Maximum temperature 29.5°C, minimum 2.7°C. A large diurnal range. Gusty at Pasadena, where at 1.50 pm (21:50 GMT) the sky was only partly cloudy (4 oktas of cumulus and stratus) and the temperature was 15°C. Relative humidity only 22%. Maximum temperature 17°C, minimum 7°C. "Sunny but breezy with high clouds" at Moses Lake in Washington State. Temperature 10.6°C at 11 am Local Time. Maximum temperature 10.6°C, minimum —2.2°C.
INTRODUCTION TO ATMOSPHERIC SYSTEMS
For information about atmospheric circulations, click here.
INTRODUCTION TO SATELLITE IMAGES
On the so-called ‘visible’ images from satellites, what you see is more or less what you would see with your own eyes if you were in the satellite and looking in black and white.
On the so-called ‘infra-red’ images, the whitest areas are the coldest and the blackest the hottest. Thus, high clouds (e.g. the tops of cumulonimbus anvils and the sheets of cirrus clouds ahead of warm fronts) show as white areas. Medium-level clouds and very cold land areas show as grey.
On the so-called ‘water vapour’ images, the whitest areas are the most humid, the blackest areas the driest. The water vapour indicated by these images tends to be in the upper half of the troposphere, not lower down.
For information on how to obtain satellite images of the highest quality, see the Notes section below.
To return to A Suggestion for Primary Schools, click here.
AUSTRALIA, NEW ZEALAND AND INDONESIA
For a chart showing isobars and fronts over New Zealand at 06:00 GMT, click here. For a chart showing isobars and fronts over Australia at 06:00 GMT, click here. The chart from the Meteorological Service of New Zealand shows that the pressure gradient over New Zealand was slack in a col between anticyclones to the east and west of New Zealand and areas of low pressure to the north and south of New Zealand. A cold front brought cloud to the North Island, but cloud amounts were small over South Island. The chart from the Australian Bureau of Meteorology shows that pressure was again high over the Great Australian Bight (1028 mb south of Adelaide) and low (1007 mb) to the south-west of Cape Leeuwin. Pressure was also low (1008 mb) over Darwin.
The visible and infra-red satellite images for 03:00 GMT show that skies were again clear and day-time surface temperatures high over most of Australia. Small areas of high cloud can be seen over the Timor Sea and central Australia, and small cumulus clouds can be seen over eastern Queensland and north-eastern parts of the Northern Territory. Tropical cumulus and cumulonimbus activity was again, like yesterday and the two previous days, extensive over Melanesia. The ITCZ was again weak between Australia and south-east Asia, with cloud amounts small over Singapore and Indonesia, though, as the 08:00 GMT visible and infra-red satellite images show, cumulonimbus build-up did occur in some places.
For the Australian Bureau of Meteorology's archive of weather maps and satellite images, click here.
INDIA AND THE INDIAN OCEAN
Today’s 08:00 GMT visible and infra-red images from the INDOEX satellite show that cloud was again, like yesterday and the day before, extensive over north-western parts of India. For a possible explanation of the cloud’s formation mechanism, please refer to the MetLink report for 12 March (in the section of ‘Today’s Analysis’ entitled ‘India’). As these images show, skies were largely free of cloud over eastern and southern India, Bangla Desh, Assam and Myanmar (formerly Burma).
The reflection of the sun off the ocean east of the Seychelles can be seen on the visible image. At the present time, just a week before the equinox, the sun’s declination is about 2.5°S. A week from today, the sun will be overhead at the equator.
Tropical Cyclone Hary can be seen south-east of Madagascar. So, too, can the cloud patterns of depressions over the Southern Ocean, showing up particularly brightly on the visible image. Hary was today moving south-eastwards at a speed of about 11 km/h. For close-up views of this storm, click here for the visible image and here for the infra-red image.
AFRICA
Today’s chart of isobars and fronts over Africa and adjacent oceans at 06:00 GMT shows that Tropical Cyclone Hary was then near 31°S 60°E with a central pressure of 995 mb. The chart also shows numerous depressions over the Southern Ocean between 40°S and 70°S, with the cold front of one of them extending to Cape Town. Pressure was low, too, off Durban. The subtropical anticyclone over the South Atlantic was centred to the south-west of St Helena (1021 mb) and pressure was high over South Africa and Botswana (1021 mb). Another High (1025 mb) was centred close to Crozet.
The 12:00 GMT visible and infra-red images from METEOSAT show that cumulus and cumulonimbus activity was extensive again today over central and southern Africa, as it was, indeed, yesterday and the day before. South of about 20°S, however, cloud amounts were small. Skies were clear of cloud over most parts of North Africa north of 10°N, and surface temperatures were high (as the blackness on the infra-red image shows). Most of the cloud that did exist was cirrus in the upper troposphere, showing up white on the infra-red image because of the low temperatures at those levels (above 10 km height). It was not conspicuous on the visible image because it was so thin and tenuous. The ITCZ was well developed over the Atlantic Ocean today, with clusters of cumulonimbus clouds close to Ascension Island.
EUROPE
Today’s 06:00 GMT chart of isobars and fronts over Europe shows an extensive area of low pressure to the west of France. This was a complex depression with three centres: one at 48°N 15°W (992 mb), another near Cape Finisterre (994 mb), the third at 47°N 5°W (996 mb). As this chart and the 12:00 GMT visible and infra-red satellite images show, fronts from the depression extended eastwards across the Celtic Sea, southern England and northern France to northern Germany, Belarus and beyond. A cold front from the depression brought cloud to eastern France southern Germany and north-west Italy. Pressure was high over southern Norway and southern Sweden (1032 mb); and fresh to strong easterly winds blew across the British Isles (for an 06:00 GMT chart showing winds over the UK and Ireland, click here). Pressure was high over the south-east of Europe and low over the Crimea. Skies were largely clear of cloud over eastern and southern Europe, as the satellite images show. For a close-up of clouds over the British Isles at 13:15 GMT today, click here.
The 06:00 GMT chart of observations over Scandinavia shows that inland temperatures were very low this morning (below —20°C) over many parts of Norway, Finland and Sweden. This chart also shows that winds were light over the whole of Scandinavia, which was to be expected, given that an anticyclone was the dominant weather system.
For a chart of significant weather over Europe at 06:00 GMT today, click here.
NORTH AND SOUTH AMERICA
For a chart showing isobars and fronts over North America at 09:00 GMT today, click here. This shows that pressure was high to the west of the USA (1042 mb) and also to the east of Newfoundland (1027 mb). It was high, too, over much of Canada, but a Low of 992 mb lay over Labrador and eastern parts of Québec Province. Another Low (988 mb) was centred over Colorado. The 15:00 GMT visible image from the geostationary satellite that views North and South America (called GOES-E) shows that frontal cloud was extensive over central parts of the USA. It also shows that cloud amounts were generally small over south-eastern parts of North America. The weather forecast chart shows that snow and freezing rain were expected over western parts of the USA.
The 12:00 GMT infra-red and 15:00 GMT visible satellite images of South America shows that cloud amounts were large again today over the northern half of South America, with many cumulonimbus clouds bringing downpours of rain. Southern Chile and southern Argentina were also cloud-covered. The cloud over the northern parts of South America was associated with the ITCZ. The cloud over southern Chile and southern Argentina was associated with a Low (990 mb) centred near 44°S 80°W. For a chart showing observations and isobars over South America at 00:00 GMT today, click here.
SEA ICE
Today’s 13:47 GMT visible satellite image from Dundee University shows that the northern half of the Gulf of Bothnia (which lies between Finland and Sweden) is presently ice-covered (as it usually is in early to mid March). Today’s 15:00 GMT visible image from GOES-E shows that Hudson Bay is also ice-covered at the moment. This image extends from the Yucatan Peninsula and Caribbean Sea across the eastern half of North America to the Canadian Archipelago. The bay in question, and its southward extension, called James Bay, can be seen at the top of the image. Another stretch of water that is ice-covered at the moment is the Sea of Okhotsk, which lies to the north of Japan. The ice can be seen on visible satellite images.
For Today’s Review of MetLink Observations, click here.
For Today’s Analysis, click here.
NOTES
INTRODUCTION TO ATMOSPHERIC SYSTEMS
To return to Today’s Headlines, click here.
To return to Today’s Analysis, click here.
1 Low latitudes
Near the equator, air rises to the upper troposphere (to altitudes of 12 to 15 km) inside cumulonimbus clouds. Over the rest of the tropics and in the subtropics, air subsides throughout all but the lowest one or two kilometres of the troposphere, where turbulence and small-scale convection prevail. An inversion of temperature marks the boundary between the subsiding air and the air containing the turbulence and convection. Trade winds blow in the lower troposphere, from the north-east in the northern hemisphere, south-east in the southern. The trades of the two hemispheres converge in a zone near the equator called the Intertropical Convergence Zone (ITCZ). Here, the cumulonimbus activity is concentrated (in clusters of cumulonimbus clouds) and winds tend to be light and variable. A belt (or trough) of low pressure accompanies the ITCZ. Otherwise, extensive areas of high pressure (subtropical anticyclones) dominate the tropics and subtropics. Where these anticyclones prevail, the weather is predominantly dry. In contrast, the cumulonimbus clouds of the ITCZ produce heavy falls of rain. This basic pattern of flow in low latitudes is known as the Hadley Cell of the atmospheric general circulation, after the meteorologist George Hadley, who first proposed it (in 1735).
2 Middle and high latitudes
In middle and high latitudes, weather is controlled by transitory depressions and anticyclones throughout the year. These weather systems are mobile and constantly changing. Therefore, considerable day-to-day variations of wind direction may occur in any given locality. Nevertheless, the winds are not without pattern: westerly winds prevail in middle latitudes and easterlies in polar regions. As winds from a westerly point occupy the equatorward flanks of depressions and easterlies the poleward flanks, the prevailing winds are consistent with the tendency for depressions to be deepest when their centres of low pressure lie between the parallels of 50° and 70°. Surface air currents flow away from the poles and are deflected by the Coriolis force to become easterlies.
3 Seasonal rhythms
Climatic zones migrate. Each zone migrates towards the pole of the summer hemisphere, reaching a point farthest from its mean position about two months after the summer solstice. Accordingly, there are seasonal rhythms in global patterns of wind, pressure and precipitation. These migratory movements are not steady; on the contrary, they tend to be intermittent. When a particular type of weather develops over an area, it tends to persist for several days or a few weeks, until a different type replaces it. Fluctuations of atmospheric state on shorter time scales also occur, because weather systems are mobile and ever-changing. They develop to maturity and subsequently decay and during their life cycles respond to local influences such as the temperature of the underlying surface. Thus, in any given locality, weather varies not only from season to season but also from day to day and, especially over land, from one time of day to another.
Over the monsoonal regions of Africa, Asia, Indonesia, Australia, the Indian Ocean and the South China Sea, impressive changes in atmospheric behaviour occur at certain times of year. These changes are characteristic of the onset and retreat phases of monsoons, and they involve comprehensive and widespread reorganizations of atmospheric circulation patterns. There are changes in patterns of vertical motion such that the droughts of winter are replaced by rainy weather during summer, and there are associated reversals of wind direction at all levels in the troposphere and lower stratosphere. The reorganizations are abrupt and cannot be accounted for simply in terms of jerky meridional migrations of climatic zones. Monsoons are complex systems which owe their existence to the collaboration of several meteorological factors, among them the migratory behaviour of the ITCZ.
In all parts of the tropics, winter wind and weather patterns are consistent with the operation of a Hadley Cell. The ITCZ is active near the equator, whilst widespread subsidence occurs in the tropics and subtropics and trade winds blow in the lower troposphere. Between the east coast of Africa and the meridian of 150°E, for example, during the period mid-December to mid-March, clear skies and north-easterly surface winds prevail over India, Sri Lanka, South-East Asia and adjacent oceans, whilst monsoon rain systems and north-westerly winds affect Indonesia and northern Australia and south-easterly trade winds blow over tropical parts of the South Indian Ocean. At the same time, the ITCZ lies a little to the south of the equator. The period from mid-March to early June is one of transition over this region. Dry weather returns to northern Australia and winds become light and variable over India, Indonesia and adjacent waters.
During this period of transition, corresponding changes in atmospheric circulation occur elsewhere in the world. Thus, in the middle latitudes of the northern hemisphere, for example, the period from mid-March to early June is one of transition from the winter circulation to the summer circulation. Sometimes in these parts of the world, the winter circulation gives way to a different atmospheric pattern rather abruptly in mid-March. In the British Isles, a manifestation of this may be a return to cold weather in mid-March after a very mild winter. The opposite can also occur. In March 1947 and March 1963, for example, exceptionally cold winters ended very abruptly. The change in 1947 brought disastrous consequences in the form of severe flooding, caused by heavy rain and the melting of snow. For a feature on the winters of 1947 and 1963, click here.
Acknowledgement: Much of this feature on atmospheric circulations has been taken verbatim from the Compendium of Lecture Notes in Marine Meteorology for Class III and Class IV Personnel by J.M.Walker (published by the World Meteorological Organization in 1991).
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A SUGGESTION FOR PRIMARY SCHOOLS
As noted earlier in today’s MetLink report, the whitest areas on the so-called ‘water vapour’ satellite images are the most humid, the blackest areas the driest. Pupils in primary schools should, of course, investigate which are the wettest and driest parts of the world, and the water vapour images are very useful in this respect. Artistic pupils may, however, like to use these images differently. They may like to colour them and thus produce some stunning designs for, say, curtains, wallpaper, blouses, skirts, etc. These images often contain very pleasing swirls somewhat reminiscent of Paisley patterns. For today’s 09:00 GMT water vapour image from METEOSAT, the geostationary satellite 36,000 km above 0°lat 0°long, click here. Let the children’s imaginations run riot! To find out how to obtain more satellite images, click here.
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To return to Today’s Analysis, click here.
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ACTIVITIES FOR PRIMARY SCHOOLS
Have you tried to make your own weather instruments? For guidance on making devices to measure wind speed, click here. For a host of practical ideas from the BBC, click here. For the Project Atmosphere Australia web guide to making simple weather instruments, click here. For the UK Met Office guide to making your own weather instruments, click here.
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DOWNLOADING IMAGES FROM THE INTERNET
To download an image from the internet, you first right-click on the image. This opens up a dialogue box. You then (if you are using Internet Explorer) click on "Save Picture As" (or, in Netscape, "Save Image As"). This opens up another box which allows you to choose a name for the file, a folder (directory) to put it in and the type you wish the file to be. Click on "Save" and the image should now be saved in the folder you chose. You can now import the image into Word, PowerPoint, image processing software, etc.
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You can obtain satellite images of the highest quality from the Dundee Satellite Receiving Station, Dundee University, Scotland. First, though, you must complete an on-line registration form. Registration is free and the images are free. Do not hesitate to register. The staff at Dundee welcome new users and you gain access to images of very high quality. You go first to http://www.sat.dundee.ac.uk/ and click on the button labelled "Register for free images". All you do then is fill in the form, press the button labelled "Create account", remember the user name and password you chose and start using the site.
From the satellite station’s home page, i.e. http://www.sat.dundee.ac.uk/, you click on "Home for registered users" and then choose the images you require. I suggest you begin with "Geostationary satellite images — view the whole earth". On this page, which provides links to the latest images from geostationary satellites, you select whichever image you require. If you want an image from a previous day, choose "Archive".
Images from the following satellites are available: METEOSAT (which covers Europe and Africa), Japanese GMS (which covers the western part of the Pacific, Australia and Indonesia), US GOES-EAST (which covers North and South America), US GOES-WEST (which covers the eastern Pacific) and IODC (which covers central Asia, southern Asia and the Indian Ocean).
From all of these satellites, images can be obtained in Visible and Infra-Red formats. From METEOSAT and IODC, images showing distributions of water vapour can be obtained. From METEOSAT, colour-enhanced images of Europe can be obtained.
If you wish to view images from polar-orbiting satellites covering western Europe and the eastern Atlantic from Greenland and northern Scandinavia to western Asia and North Africa, go from "Home for registered users" to AVHRR Images — latest images or, for archived images, AVHRR Images- Archive.
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