GRACE UNDER PRESSURE

GRACE UNDER PRESSURE

Give the students a map of the UK.
Draw a large H over East Anglia, in the middle of Norfolk
Draw a circle of 5cm diameter around the H (use a compass - no one can draw circles freehand...)
Put the map flat on the desk.
Stand up.
Bring the thumb and fingertips of your left hand (assuming that you are right handed..) together and place them on the circle that you drew, so that they are inside the circle, with your thumb on one side and your fingers on the other.
Rotate your hand slowly clockwise, as seen from above (and with North at 12 o' clock) and gradually spread out your thumb and fingertips as your hand turns. Take care not to turn the map round as you do this. Practice until you can twist round as far as possible and remain comfortable.
Place your thumb and fingertips back in their starting positions and label their positions with numbers 1 - 5 (1 being your thumb and 5 your little finger...)
Slowly rotate your hand clockwise again - go about a quarter of the way through your twisting motion and stop. Mark the new positions of your thumb and fingertips on the map. Keep doing this for halfway through the twist, three quarters and when you finally finish your twisting.
Connect the numbers using a smooth curved line.
Add an arrow to the end of the line showing the direction that your fingers moved.
The spirals represent the general flow of surface air that occurs in a HIGH pressure system, or ANTICYCLONE.

This can obviously be done in reverse: start with finger and thumb spread out, and bring them in towards the centre in an ANTI-CLOCKWISE movement.

Remember BUYS BALLOT's LAW:

if you stand with your back to the wind in the Northern Hemisphere, low pressure is on your left hand side and high pressure is on your right.