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File: 950825_22tr1018_143.txtFilename: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 agentŐs 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 agentŐs 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 agentŐs 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 agentŐs cloud after the areas are totally invaded by the wind. After the cloud of the toxic chemical agent passes above buildings, the agentŐs 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 agentŐs 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 agentŐs 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. CloudŐs 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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