-9tropies, an increase of temperature with height in the stratosphere.
Second, tha stratosphere is practically cloudless and hag no
precipitation falling from it.
‘hs first difference mans that
there is very little vertical turbulence in the stratosphere
_
compared with the troposphere, so that vertical turbulent mixing
is much slower.
The absence of clouds msans that the removal
of debris cannot bo aided by falling precipitation elexents,
Toe absence of mixing in the vertical coordinate does not
preclude horizontal diffusion, and in fact, Parr's principle,
would suggest that horizontal mixing might be greater an account
of the lack of vertical mixing.
However, excspt for the spread .
of dust from rake 2G,bubreis1itthe or no evidence on sither
side,
Untortmately,” the optical detection of the Erakatso dust
is not quantitstive in the sense that it is possible to assign
concentrations to the spread of the dust.
There 4s reason to
belleve that the equatorial band of tha lower stratosphere may
prevent exchange of air between the hemispheres just as is
the case for the lover troposphere, In the troposphere, it is the
convergence of air into the Intertropical Convergence Zone, _
as shoom in Figure 5, which prevents exchange,
In the lower
stratosphere, it is the stesdiness of the east to vest wind vhich
would suggest little or no north-south exchange, This point is
of som consequence,
It my mean thst the hemisphere with the
atomic teste will obtein a disproportionate share of dslayed fallout.
Oa the other hand, the measurezent of delayed fallout in the southern
hemisphere reans that soma stratospheric dstris mst have come into
the southern hemisphers.
Conesivably, the path of the debris may be
through the northern hemisphere tropopause and then to the southern
henisphere yia the upper troposphere,
ae