MetLink Activity 14 (age 16+)

Please see the note at the end about application of this activity to world areas other than the UK.

Weather Changes in the British Isles
Monday 30 January to Thursday 2 February 2006:

This activity is designed for use with students aged 16+ years. In England and Wales, these are AS and A2 Level students; in Scotland they are young people studying for Higher Grades.

The aims of this activity are:
+ to use ICT skills in finding information, particularly the selection and extraction of data appropriate to a specific task
+ to use mapping and graphical skills in presenting information and making use of standard weather mapping symbols
+ to describe how weather conditions change with time and in different locations
+ to interrelate and attempt to explain weather conditions.

The Activity:

You need the following:
+ Large outline map of the British Isles.
+ Atlas. If you have access to Microsoft Encarta that would be good. Or you can use an atlas book.

1. Go to the MetLink observations database by using the MetLink Home page

+ Click on Data central
+ Click on Search observations
+ Click on the Country drop down menu and select UK – United Kingdom
+ Make sure the dates are set correctly to 02 February 2006
+ Click on Search now

This shows you all of the observations made by MetLink participants around the UK for the day.

1. Data selection: Select a number of participants’ observations to study. A suggested number is approximately 15. The criteria, in order of importance, are:
   + A widespread distribution to cover as much of the UK as possible.
   + Only select those which have a full range of data.
   + Try to select them all from a similar time block. For example, at the time of writing, there were 22 sets of observations logged between 07:30 and 09:15. From those, eliminate any without a full set of observations. This will leave you with approximately half the number. So continue on up through the data, selecting full sets until you have 15. A trial run carried out by the writer found 15 complete sets by 10:45.
   + Next you need to find out if the same participants logged observations on Monday 30 January. To do this, reset the first date on the drop down menu to 30 January 2006 and enter each participant’s name in turn in the Name contains box. If the participant has recorded data on both days, then copy and paste just the block of data and column headings into Word (with Page Set-up on Landscape). Repeat this until you have 15 sets of data. You may have to select from further up the data list to achieve this (i.e. from later in the morning). On the trial run by the writer of this piece, at least 15 were found by approx 12:30, in other words for what could loosely be described as the morning.
   + Finally, you need to check the locational spread. Some locations are obvious, for example Birmingham, and their positions can be plotted straight onto the map. For others, you will need to type in the name again and when the records come up, click on the name. After each search, you will need to return via Data central and Search observations to be able to type in the next name. In the trial, the writer found a reasonably good spread from the morning list. It has to be remembered, though, that this is a relatively small data-base and the location of participants is random (unlike, for example, the Met Office spread of weather stations across the country). It may be possible to improve the spread of your selection, but something else will now have to be compromised, such as selecting a participant from much later in the day, or one with possibly one element of data missing. That is your decision.
2. Plot the data on two separate maps, one for 30 January and the other for 2 February. Plot the data for each location using the standard Met Office key, which you can obtain by clicking here.
   For temperature, use both the maximum and minimum values.
   For cloud types, use the following letter codes:
   High-level clouds: Ci Cirrus; Cc Cirrocumulus; Cs Cirrostratus
   Medium-level clouds: Ac Altocumulus; As Altostratus
   Low-level clouds: Cu Cumulus; Sc Stratocumulus; St Stratus
   Clouds of considerable vertical extent: Ns Nimbostratus; Cb Cumulonimbus.
   To find out more about cloud descriptions, please click here.
3. Describe the changes that have occurred in the weather at each place in terms of:
   1. Temperature
   2. Precipitation
   3. Wind direction and force
   4. Cloud amount and type
   Overall has there been much change or little change in the weather of each one?

2. Compare the satellite images for the UK on the two days by clicking on the days below. Remember that on the infra-red image cold cloud which is at high altitude appears white. If it is a rather “thin” white, then it is only a high-level cloud such as cirrus. If it is a very intense white this means the tops are at high altitude, but there is a considerable vertical extent of cloud below. Low cloud is much warmer and appears grey on the infra-red image.

Important! Double click on each satellite image to increase its size on the screen and to therefore give what is called high resolution (i.e. a lot of fine detail).

Compare the infra red images for 30 January and 2 February.
Compare the visible images for 30 January and 2 February.

Describe any changes you can see in the cloud types, patterns and distributions. Overall has there been much change or little change?

3. Influences on the weather: The weather is influenced to a large extent by the distribution of areas of high atmospheric pressure (anticyclones) and areas of low atmospheric pressure (depressions).

+ Anticyclones are shown on weather maps with the letter H. The pressure values (mb = millibars) are shown on isobars (lines of equal pressure) which form roughly circular patterns around a high. The values increase towards the centre of the system. Winds blow clockwise round highs in the northern hemisphere and anticlockwise round highs in the southern hemisphere.
The air descends in the middle and lower troposphere in an anticyclone and flows outwards from central areas of the high towards its edges. Usually the outward flow is fairly gentle. As the air descends, it is warmed (at 9.8°C/km) and therefore produces no precipitation. Where the descending air meets the air which is flowing over the ground, an inversion of temperature forms, with the descending air warmer than the air beneath. The air beneath the inversion can be quite cold in winter and the air just above the inversion can be several degrees warmer.
Anticyclones sometimes produce fine weather with clear skies. On other occasions, however, low-level cloud and pollutants become trapped below the temperature inversion. When that happens, the high produces overcast, dull and gloomy weather.

+ Depressions are shown on weather maps with the letter L. They are the complete opposite of anticyclones. Complete this simple table to show this:

Features	Anticyclones	Depressions
Pressure towards centre	Increases
In N Hemisphere winds circulate	Clockwise
In S Hemisphere winds circulate	Anti- clockwise
Vertical movement of air is	Downwards
Surface winds move	Outwards
Force of surface wind is	Gentle
The vertical movement of the air causes	Warming
Condensation and precipitation	Little or none

The other features in the atmosphere which greatly affect the weather are fronts. They are shown by solid lines with either semi-circles or triangles or a combination of both drawn on one side of the line in the direction in which the front is moving. Fronts form the boundaries between air masses of differing temperature and humidity, and along their lines the warmer less-dense air rises over the colder more-dense air. The rising air is cooled, which results in the condensation of water vapour within the air and the formation of cloud and precipitation.

For further information on depressions and fronts, please click here.

Study the weather map for Europe for 12:00UTC on Monday 30 January (click here):

a. Describe the positions of anticyclones, depressions and fronts on Monday 30 January in relation to how this seems to be influencing the weather of the British Isles. To do this, you will also need to refer to the Weather Overview map for Europe (click here). The important element shown on the map you need to consider is temperature. The colours show temperatures. The lowest temperatures are shown in blue and the highest in red. Other temperatures are shown in green or brown or yellow. A scale at the bottom of the picture shows you the temperatures that correspond to each colour. Deep blue, for example, shows temperatures below minus 20 degrees Celsius. Yellow shows temperatures between 0 degrees and plus four degrees Celsius. The colours are shown over both land and sea.

b. What changes have taken place in the positions of the anticyclones, depressions and fronts by the time of the weather map for Europe at 12:00UTC on Thursday 2 February ((click here)?
How does this seem to have influenced the weather? You will need to refer to the Overview map for Thursday 2 February to help you, so click here.
c. Overall, has there been little or much change between the two days in terms of: (i) the weather and (ii) the pressure maps?

Adaptation for use in other areas of the world:

This study format can be applied to areas of the world other than the UK, but only by using a different data base for the critical data in Question 1. This is because within the MetLink network, only the UK has the necessary number and locational spread of participants over a relatively small area to make this work effectively.
There is an alternative, slightly different activity for Europe, Educational Activity 13, which has a target age of 14 to 16 but which could very easily be adapted for 16+ study.

For other countries in other world areas, the following data base is recommended as a very good basis for this Activity 14:
www.wunderground.com

This can then be backed up by resources from MetLink. Please select the resources you wish to use from the gallery obtained by clicking on these links:
Monday 30 January – click here
Thursday 2 February – click here
Unfortunately a weather overview map is unavailable for other world areas, although you may find useful materials by carrying out a web search of your own country’s weather service.