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Filename:22tr1018.143
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This document is a captured Iraqi military record.
It is provided in its original form to include Iraqi
classification markings (i.e. Top Secret, Secret, etc.).
These classification markings are NOT U.S. Government markings.
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Annex E
Effects of weather conditions and the nature of the ground (area)
on the use of toxic chemical agents
1. General
Assessing a cloud of a toxic chemical agent in a chemical
operation depends on a full and accurate prediction of the
weather conditions in the area. The main weather factors that
must be taken into consideration in chemical operations are:
the temperature and its radical change, winds, precipitations,
and the nature of the area. The most important factor is the
radical change in temperature when using chemical ammunition. Although
these factors affect the effects of toxic chemical agents that
reach the ground, they are very important because they affect the
performance of chemical clouds. When evaluating the possible
effects of toxic chemical clouds, the target analyst can rely
on the following matters only: the simple calculation in the
evaluation, the face values of the weather information, the
basic methods to estimate ammunition requirements, and the effects of
the agent.
Analysts also have to take into consideration general conditions
that surround toxic chemical clouds during the whole period of
their possible effects. By depending on expertise, study, and
the best information that can be obtained about weather conditions
and the ground in the operation unit, analysts have to determine
the possible paths of the toxic cloud movement and the period during
which the cloud is expected to stay. They also have to take into
consideration the general effects of the weather in addition to other
factors that affect the target area. They also have to take into
consideration the effects of the possible changes in weather
conditions that have an effect on the chemical cloud in a
limited period of time. No matter what, the characteristics of
the areas have to be considered also.
In order to review more details about the ground and weather conditions, refer to the
manual that pertains to the performance of toxic chemical, biological, and radiation agents
in field number ( )
2. Weather information sources
a. Weather forecast stations in artillery and missile units provide basic information
that are required about weather conditions in addition to information that are
provided by chemical units about weather conditions. Additional information
about weather conditions can also be obtained by the operation troops through the
following:
One. Air surveillance and reconnaissance
Two. Ground surveillance and reconnaissance
Three. Fog, smoke, and dust surveillance within the operations troops
Four. The appropriate field methods to obtain weather information near the
target area
Five. Confirmed studies about weather conditions in the operations field
b. Appendix (1) of Annex F lays out a suggested form to send and record basic
weather information.
It has been confirmed that during the analysis of a chemical target, weather
forecasts are required for a period of time after the attack as well as during the
chemical attack.
c. The target analyst may obtain information about weather conditions, accurate
forecasts from air force units, and chemical units.
3. Temperature
The evaporation level of the toxic chemical agents increases with the temperature increase.
This leads to reducing their persistency period. High temperatures also lead to excessive
sweat by people and therefore, skin pores open up and speed the penetration of the toxic
chemical agent into the skin. At low temperatures, additional layers of clothing help
forming a barrier against the penetration of a chemical agent into the skin.
4. Radical change in temperatures
The radical change in temperatures is used for the difference in air temperature at two
levels.
They are determined by subtracting air temperature that is taken at an altitude of 50 cm (_
meter) above the surface of the ground from air temperature at an altitude of 2 meters
above the surface. The three conditions that are related to the radical change in
temperatures are:
a. Unstable condition
It is the condition that is accompanied by a decrease in air temperature when
above the ground. Usually, such a condition is evident on a clear or partially clear
day. It is the least required condition for chemical operations due of the quick
dispersion of the toxic chemical agentÕs clouds.
b. Stable condition
In this condition, air temperature increases with the ground altitude. This
condition is accompanied by less turbulence. It occurs usually during clear nights ,
partially clear nights, or in early in the morning. It is the best condition for
chemical operations because toxic chemical agents cloud remain in cold air pockets
near the surface of the ground.
c. Equilibrium
It is the condition that ranges between stable and unstable. Such condition prevails
when there are few differences in temperature at both levels. It usually occurs on
cloudy days or nights after sunrise and shortly before sunset.
5. The wind
The wind is also considered one of the important weather elements that affect the
performance in the field of toxic chemical clouds. The wind characteristics are velocity and
direction. Both these factors are affected by the nature of the ground and the radical
change in temperature.
a. Velocity
Air creates above an uneven surface, circles or mechanical turbulence. This
turbulence resembles that of temperature since it aims at dispersing the toxic
chemical cloud. The high velocity wind makes the agentÕs cloud pass very quickly
above the target area. This shortens the period of exposure to the toxic chemical
agent. Some action in the air will be required for the purpose of mixing isolated
clouds of the toxic agent. Those clouds consist of each shell explosion since they
result in a cloud that covers the target. The ideal wind velocity of the chemical
operations is about 6 to 16 Km / hour or 1.6 to 4.4 m / second. As to the wind
velocity that does not exceed 30 km / hour or 8.3 meters / second, it is
inappropriate because of its unconfirmed effects.
b. Direction
The direction of the chemical cloud should be taken into consideration when
launching a toxic chemical agent to cover a certain target and determine the danger
caused by the downwind direction for our troops. The direction of the wind is
where the wind blows. It is measured in degrees.
6. Precipitations (Rain / Snow)
Precipitations have a counter effect on the performance of toxic chemical agents since rain
washes away the contamination of liquid chemical agents and snow covers it.
Precipitations also washes away a chemical agentÕs vapors or aerosol clouds and
demolishes some toxic chemical agents with the effect of water solubility.
7. Sea breeze
When air that is at low level on the ground near the sea is warmer than the air above the
sea, air breeze is formed. For example, air tends to blow from the sea to the dry land. This
means that winds that are coming from the sea come slightly closer together with the
winds that come from the dry land . At the joint point, winds go up to a higher level. This
often occurs within a tight and parallel belt to the sea borders. During the day, this belt
moves from the dry land and may continue till the evening. This belt is known as the sea
breeze front. In fact, this front works as a barrier to penetrate the toxic chemical agents
that are launched from the sea towards the grassland and carry these toxic chemical agents
high then heads back towards the sea but at high altitudes. If toxic chemical agents were
launched in the dry land
of a sea breeze front, they also blow towards the front then are carried up. There is a
chance of mixing with the sea air and dispersing towards the bottom at a distance towards
the sea.
8. Land breeze
It is the opposite of the air breeze process since it blows from the dry land to the sea and
passes through the sea coast. This occurs during clear and cold nights when the air at a
low level on the ground becomes colder than the air in the nearby sea. Nevertheless, land
breeze is very weak and is often ignored in chemical operations matters.
The nature of the ground
9. The elevations
Ground elevations change the direction of the cloud and may shatter clouds. Low and
high elevations retain parts of the toxic chemical agentÕs cloud after the areas are totally
invaded by the wind. After the cloud of the toxic chemical agent passes above buildings,
the agentÕs vapors that have penetrated tend to remain there for long periods.
10. The surface
The surface of the ground affect the size of the toxic chemical agentÕs cloud, the size of
the hole, the contamination level of the toxic chemical agent, and the effect of the
explosive ammunition.
a. Loose ground
Chemical ammunition and bombs do not explode on a loose ground surface but
deep in it. Thus, a part of the chemical agents remain in the formed hole. The
formed toxic clouds are also less concentrated than in the solid ground.
b. Solid (Firm) ground
Almost no losses of toxic chemical agents occur when explosive type chemical
ammunition fall above the solid ground. Liquid toxic chemical agents contaminate
the surface and cause a risk when touched. Toxic clouds that are formed are more
concentrated than in the loose ground.
c. Porous ground
If liquid toxic chemical agents fall on a porous surface such as earth, sand etc., the
toxic chemical agent quickly spreads inside the surface and loses some of its
characteristics. In addition, the evaporation level from the surface is far slower
than that of the non porous surface.
11. Plants
Toxic chemical agents that spread on plants usually endanger troops more than those that
are on bare or solid ground. More effective concentrations of the toxic chemical agentÕs
cloud may appear in the persistent air that surround the bushy area.
Appendix (1) of Annex E
Sample of a chemical (biological / radiation) weather forecast
Forecast time / Time, Date
and Forecast Time + ( )
hour
1. Area covered by the forecast
Area for which the division is responsible
2. Wind
a. Direction
in degrees
b. Velocity
One. At an altitude of 2 meters or 6 feet / ..... (knot / second) or meter / second)
Two. At an altitude of 100 meters or 300 feet /... (Knot / second) or (meter /
second)
3. Air temperature (FO / CO)
One. At an altitude of 2 meters or 6 feet / ..... (FO / CO)
Two. At an altitude of 0.5 meter or 1 foot / ....(FO / CO)
4. Soil temperature/ .....(FO / CO)
5. Condition of radical change in air temperatures
If it were:
Air temperature at an altitude of 2 meters or 6 feet - air temperature at an altitude of 0.5
meter or 1 foot
= - 3 Fo below [stable condition]
= +- 2 Fo [equilibrium]
= + 3 Fo above [unstable condition]
6. Relative humidity
7. Precipitations (rain / Snow)
(Low, medium, high)
8. Visibility
9. Toxic chemical cloud
a. Cloud cover
Clear, dispersed, irregular
b. CloudÕs altitude
One. Low > 1000 feet or 300 meters
Two. Medium > 5000 feet or 1500 meters
Third: High < 5000 feet or 1500 meters
10. Isolation (Sun radiations)
(yes at first)
11. Fallout winds
Forecast time to (forecast time + 6 hours)
a. Altitude
b. Direction
c. Velocity
Note
In order to convert the centigrade temperature to a Fahrenheit temperature and vice versa,
the following equation is used:
Co = 5 / 9 x (Fo- 32) or Fo = 9 Co + 160 / 5
Co = Centigrade temperature
Fo = Fahrenheit temperature
Example:
1. Convert 5 Co to a Fahrenheit temperature
Answer:
Fo= 9 Co + 160 / 5
Fo= (5x9) + 160 /5 = 205 / 5 =41
Fo= 41
5 Co = 41 Fo
2. Convert 50 Fo to centigrade
Answer:
Co= 5/9 x (Fo- 32)
Co= 5/9 x (50 -32)
Co= 10
50 Fo = 10 Co
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