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File: 950825_22tr1018_143.txt
Page: 143
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Filename:22tr1018.143
*********************************************
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.
*********************************************
											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 agent�s 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 agent�s 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 agent�s 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 agent�s cloud after the areas are totally 
invaded by the wind. After the cloud of the toxic chemical agent passes above buildings, 
the agent�s 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 agent�s 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 agent�s 
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. 	Cloud�s 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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