- NOAA interactive (uses recent balloon data) revised November 2007|
is the header you get when you get to the web page (via link above) http://rucsoundings.noaa.gov/
|Link on right is also on the main weatherjack weather page|
now get a table with click boxes. ('RAOB'
= (RAwinsonde OBservation). This
example below is from an excellent day Thursday, 9th August 2007
can be left alone, but some of those starred will probably need to
be altered. RAOB is the usual selection.
Start time can be latest or a particular time for archive study.
The example is for Year 2007, month August, date 8th, time 23:00 UTC, ie the final sounding before the start of 9th August.
of hours can be left at 3.0 (number is in connection with animated
soundings but not available for UK stations) but this covers the
uncertainty exactly when the balloon is sent up.
Site is selected from list below but note is is IMPORTANT to include the leading zero.
PRACTICE you will probably want to make a forecast for the coming day.
Use the midnight sounding (probably in practice 2300 from day
up to date forecast maximum temperatures, expected dewpoint (likely
similar to dewpoint at 0700 hours) and sea level pressure.
is a Skew-T and you can work out a great deal simply by looking at this
there is much more.
positioning the mouse, left clicking and dragging, you can zoom in on the
main area of interest
click. This box appears.
necessary, click or fill in the boxes. It is easy to forget to click Celsius.
In this box, Td means dewpoint, T means (dry) temperature.
Archive temperatures, dewpoints and pressure best found from this website
you can move the mouse pointer to an appropriate place, usually ground
level and a surface temperature, and left click. (playing with high
level instability is instructive).
this method does not allow change in surface dewpoint
can try various surface temperatures to see what happens, eg determine
the trigger temperature, or the temperature to give cloud base of 3,000
the result. The solid horizontal black line is cloud base for the
Tdry and Tdew that had been used.
shallow cumulus should occur at around 4,600'
split * 400 gives similar answer but the Bradbury Rule does not work
for blue thermals so this SkewT is useful in that it shows that small
cu are likely to form and that thermals are not blue.
can alter the temperature, work out trigger, cloud tops, etc.
is a superb program. You can try various "what ifs". Experiment
and have fun.
are many other features that have not been covered. This explanation
is just to get you started.
available on the website itself.
in bold normally report midnight and midday UTC.
are occasional although Larkhill (for the Salisbury Plain gunnery) usually
sends up a balloon at 0600 GMT Monday to Friday.