East Asia and Western Pacific METEOROLOGY AND CLIMATE

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The experiment was repeated many times with different specific
gravities of saline solution at both ends. Collisions between gravity
currents formed from specific gravity 1.01 with those formed from 1.01 to
1.04 at 1% increment were performed.
RESULTS AND DISCUSSIONS:
The experimentally determined velocities of the gravity currents
are shown in Figure 2.
shown in Figure 3.
The composite photograph of experiment run 6 is
In that run the specific gravity of saline solution on
the left side was 1.01 and the specific gravity of saline solution on the right
side was 1.03.
For collision of gravity currents of substantially different specific
gravities, the qualitative behaviours all showed similar features. The
velocity of gravity currents did not alter appreciably before collision.
After colliding, the denser fluid slid under the less dense fluid with some
mixing. A hook shape overspill of less dense fluid was always observed.
The maximum height of the overspill could reach to more than five times of
the gravity currents. This hook engulfed the ambient fluid (fresh water).
Since the ambient fluid was lighter, instability occurred resulting in
vigorous mixing. The lifting of a colder mass of air in the sea breeze or
thunder storm outflow into great height was the cause of severe weather
and the lumpiness seen on the radar.
In comparison with observation, two characteristics of sea breeze
collision were reproduced in the laboratory. After the violent collision a
reformed sea breeze moved forward at a slower velocity for the stronger
sea breeze and a reflected solitary wave (or bore) was observed. These were
modelled by the laboratory collision of gravity currents. For more
discussion on the comparison please refer to Kot and Simpson (1987).