[coollycat]

Two aircraft are flying side-by-side at 200 kmlh toward the east at the 4 km level near
55 N latitude, with a 65 kmlh tailwind from the west. One aircraft has a radar altimeter which measures exact height above the ground, while the other aircraft has a pressure altimeter. They both turn to fly directly northward,maintaining their speed and keeping their altimeters reading 4000 m.

a) Estimate how much (higher? Lower?) the aircraft with the pressure altimeter will be than the other aircraft after 1 hour of northward flight. Show you have checked units.

b) One of the aircraft now descends to land at an airport that is 420 m above sea level.
The station temperature and pressure are 10 C and 981.4 mb. Estimate the pressure that would be plotted on the surface weather map for this station. Show you have checked units.

c) Near the surface at this airport (57 latitude), the pressure gradient force is 9.2 x 10-4 NI kg. Calculate the spacing (km) between isobars drawn at 4 mb intervals. Show you have checked units.

d) With quite smooth terrain around this airport, the 10 m wind is blowing across the isobars at an angle of only 30 degrees. Estimate the wind speed. (Hint: determine CH from a force diagram.)