Click on a coloured dot on the map for related soundings. Hover cursor over the dot for name and RAOB number. Those in red normally report midnight and midday UTC. Others yellow) are occasional although Larkhill (Blue) (for the Salisbury Plain gunnery) often sends up a balloon at 0600. Click here to load all red stations in one go.
Warning: Check the date displayed to ensure currency - some stations only produce data intermittently.
Note: A midnight sounding might be labelled 2300 the previous day
Instructions: Once the chart appears and you have checked the date and time position the cursor on the bottom line at the expected temperature eg T:26 (79F) 1016 mb and then click or right click and enter Td (Dewpoint Temp), T (expected ground temp) and P (expected ground pressure).
This purple line represents the way air would rise in a thermal from surface temperature of 26°C.
The black line represents the anticipated dew point (cloud base) if the purple line intersects the red line before the black line then a blue day is forecast otherwise the vertical distance between the black line and the insect of the purple and red line represent the expected cloud height. By positioning the mouse, left clicking and dragging, you can zoom in on the main area of interest.
The red hatched area width gives an indication of thermal strength. The wider it is the stronger the expected thermals.
Full tutorial here; Detailed instructions for Java Soundings applet here