[Milsurplus] AN/AMT-3

[David I. Emery]

On Wed, Sep 26, 2018 at 12:49:29PM -0700, Brooke Clarke wrote:
> One question is why you called it a Dropsonde rather than use the label 
> designation of Radiosonde?

	There have always been pretty much two radio based weather
telemetry devices in wide continuing use  to sample the various layers
of the atmosphere at some time and place and telemeter this back by
radio to a ground or airborne data collection site.

	Radiosondes have traditionally been the balloon kind - launched
from the ground or a ship - attached to a latex weather balloon filled
with hydrogen or helium;  balloons which typically rise to something
around 90,000 to 120,000  feet at around 1000 feet per minute and then
burst allowing the radiosonde to descend on a parachute (mostly for
safety, they are only occasionally actually recovered and reused).

	Mostly these are routinely launched once every 6 or 12 hours
from a network of fixed sites scattered across continents to provide
profiles of wind speed and direction at various pressure altitudes, and
temperature and relative humidity at those pressure altitudes which are
used as inputs to numerical weather models run on supercomputers that
compute from that initial state information what will evolve in the
atmosphere on a global scale hours and days into the future.  Other
inputs from aircraft reports, ground station reports and satellite
observations also initialize these models but the upper air data from
radiosondes remains consistent information at particular places more or
less always there and is important.

	Dropsondes are a similar technology using devices dropped on
parachutes from aircraft used to sample the atmosphere in places where
launching a balloon from the ground or a ship is  less practical or
completely impossible.    Mostly these are used by weather
reconnaissance aircraft to sample the atmosphere in and near major
storms such as  hurricanes and typhoons and other large and dangerous
weather systems - often several launched in rapid sequence  as the
aircraft makes a pass through (or over) the core of a storm with data
collected from  multiple units at once on different RF channels.

	AFAIK there aren't many sites where dropsondes are routinely
used (unlike radiosondes which are launched at many tens  of sites world
wide multiple times a day) but are mostly reserved for situations where
weather data about powerful storms or over oceans is needed for critical
forecasts.

	For various reasons dropsondes and radiosondes are not usually
the same hardware, but similar in conceptual design.

	
-- 
  Dave Emery N1PRE/AE, die at dieconsulting.com  DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in 
celebration of what could have been, but wasn't and is not to be now either."