Proceedings: 3rd Tall Timbers Fire Ecology Conference 1964

The Natural History of Lightning

E. V. KOMAREK, SR. Tall Timbers Research Station

THE NATURAL history of a subject such as lightning is fraught with pitfalls in both observation and interpreta­ tion, but when we delve into natural processes this is generally true. It b.ecomes particularly so with a subject that travels with "lightning speed." In fact, it is so quick that lightning current durations are measured in microseconds-millionths of a second. It is a short piece of time, when you consider that a microsecond is to a second what one minute is to 23 months, or what one inch is to 16 miles. (Towne 1956) This gigantic spark, electrical charges rushing to meet their oppo­ sites, has a core of electrical energy which may be ten or more inches in diameter but generally ranges from Yz to % of an inch. This is sur­ rounded by a channel of intensely-heated air several inches thick. The voltage rises hundreds of thousands of volts, and the current has been measured as high as 340,000 amperes. The length of the stroke may be 15,000 feet or more, but the average has been given as about 4000 feet. The bolt or lightning flash we see is actually made up of many repeated currents traveling back and forth from cloud to earth, much like a vast sewing machine with electricity as its thread. As many as 47 separate strokes have been counted, and these may come very quickly or be spaced as much as a half second apart (Fig. 1). The primary generator of this tremendous electrical discharge is the thundercloud or thunderstorm, and the popular phrase, "where there is thunder there is also lightning" is well stated. Every thunder-

139 Fig. 1. A lightning storm in the prairie state of Kansas. Photo by U. S. Weather Bu­ reau.

storm is made up of one or more "cells" which consist of downdrafts and updrafts. When humid air is brought into the "generator," it con­ denses into raindrops. These toss about and turn to ice crystals inside the violent air currents. As a consequence, there is a separation of electrical charges, the positive usually, though not always, concen­ trate in the upper portion of the cloud mass and the negative in the lower section. As the thunderstorm travels across the surface of the ground, the potential of the earth's surface and anything on it, which in fair weather is negative switches and becomes positive. Thus we get a situation where there are positive charges in the upper part of the thundercloud, negative charges in the lower part, and positive on the surface of the earth. When these charges become strong and the air is no longer able to keep them separate, we get the electric spark we call lightning. It can be from cloud to cloud, within the same cloud, or from cloud to earth, and its intensity depends much on the size and intensity of the "generator," the thundercloud itself. Gen­ erally, the larger and taller the thunderclouds, the more lightning there is both in amount and intensity (Fig. 2).

140 + + + + Fig. 2. Diagram of a thunderstorm cloud showing distribution of electrical charges.

During fair weather there is a slow leakage of negative electricity from the earth because air is not a perfect non-conductor. As the thundercloud approaches, this charge changes by induction to aposi­ tive charge and this "leakage" or leader becomes stronger and literally reaches upward because of the strong negative attraction at the base of the cloud. These accumulations, both in the cloud and on earth, become extremely large because of the mass of the cloud and the earth below it. If we could see this effect in vegetations as a thunder­ storm approaches, we would see waving electric leaders of positive charge and these leaders, given the same conductivity, will be longer, and larger, depending upon the height of the vegetation. This is why lightning usually will strike the highest objects although this is not always true because of the difference in the conductivity of the sur­ face and perhaps for other reasons (Fig. 3). This electrical phenomena occurs where-ever the type of clouds called thunder-clouds or cumulo-nimbus clouds are found. It has been estimated that th~r~ are 100 lightning "bolts" for every second 0f the

141 E. V. KOMAREK, SR. day and for every day in the year in our atmosphere around the earth (Fig. 4). This means that in the short time that I have been speaking several thousands such flashes have occurred. Of course, many of these

Fig .. 3. Diagram showing leaders from ground and leaders from thunderstorm cloud overhead. never reach the ground and occur from cloud to cloud or within the clouds themselves. However, there have been various estimates of the lightning flashes to the ground ranging from 6 per square mile in England, to 20 per square mile in Transvaal, South Africa to the fol­ lowing estimate for the United States: There are from 40 to 80 lightning strikes per year within the aver­ age square mile in this country. You can compute the number of strikes you may expect in your particular square mile by estimating one or two strokes for the number of thunderstorms in your area. If your area, for instance, has 50 storms yearly expect from 50 to 100 lightning bolts to hit within a half mile of your house this year (Lightning Protection Institute). Meteorologists have recorded thunderstorms on the basis of "thun- derstorm days." By international agreement, a "thunderstorm day" is defined as a local calendar day on which thunder is heard. A thunderstorm day is recorded as such regardless of the actual number of thunder­ storms occurring on that day. When a storm begins before mid-

142 Fig. 4. Lightning during thunderstorm in Boston. Photo by U. S. Weather Bureau.

night and ends after midnight, two thunderstorm days are record­ ed. These records, therefore, do not give information on either the frequency of occurrence of individual thunderstorms, or on the intensity and duration of thunderstorms. Lightning without thun­ der is not recorded as a thunderstorm. The requirement that thunder should actually be heard limits the area covered by each observing point to a circle with a radius of some 20 km.; this restriction almost entirely eliminates the possibility of the same thunderstorm being recorded by more than one station. On the other hand, observations of thunder are af­ fected by the "personal equation" of observers and, as Dr. C. E. P. Brooks says in his paper "The Distribution of thunderstorms over the Globe": "Thunderstorms which pass directly over the station may be noted, but those at a distance of several miles are often ig­ nored; this is specially the case in tropical regions where thunder­ storms are severe but extremely local-at certain times of the day in the rainy seasons distant thunder is so common that it simply does not occur to the observer to enter it in the register. For this reason the number of days are probably too low at many of the second and third order stations." (WorId Meteorological Organi­ zation, 1956).

143 E. V. KOMAREK, SR. The "thunderstorm day" data gathered together by this organiza­ tion, is the best information available on the thunderstorms on a world wide basis. It will be noted from their maps that there are not many regions of the world during the years these data were gathered that were free of these "lightning generators." Nationally, the U. S. Weather Bureau has gathered together the data on thunderstorm days which are more detailed and perhaps. more accurate for United States (Fig. 5-6-7). It is of interest to note in passing that these lightning flashes "fix" a considerable amount of nitrogen from the air and this is brought to earth in the form of nitric and nitrous acid by rains. The amount pro­ duced has been variously estimated at more than 100,000,000 tons yearly, 250,000 tons a day, or as much as two pounds of nitrogen per acre per year. Now lightning is but an expression, spectacular to be sure but still only an expression, of a vital force or process in nature. The structure of matter itself consists of, or at least involves, positive charged parti­ cles (protons), negative charged particles (electrons) and those par­ ticles with no electrical charge or in a neutral state (neutrons). This force was first named "electrics" by Gilbert in 1600 because of the effect obtained when amber was brushed and "electron" is the Greek word for amber. Benjamin Franklin in 1746 found that like charges repelled each other but that opposite charges attracted each other and thereby tended to combine and neutralize one another, or in other words to develop into a neutral state. He named these opposite charges so attracted to each other as "positive" and as "negative." To­ day we know that we live in an "electric" universe and that electrical energy is a fundamental force on earth; that living cells are them­ selves but miniature batteries and that you and I are in many respects living electrical machines. In late 1800 and early 1900 many investigators became interested in the electrical properties and potentials of plants as well as the effect of electricity on the plants themselves. Stone (I903, 1904, 1914); Kinney (1897), at the Massachusetts Agriculture Experiment Station, and others, found that plants not only varied in electrical potential from species to species, but from winter to summer in the same species, and that certain parts of vegetations were better con­ ductors of electricity than others. The -cambium layer in some trees

144 Fig. 5. AnnuaL distribution of thunderstorm days in North and South America. (From World Meteorological Organization-1956)

145 Fig. 6. Annual distribution of thunderstorm days in Europe and Africa. (From World Meteorological Organization-1956)

146 ----'---'-~~-.

'. -

Fig. 7. Annual distribution of thunderstorm days in Asia and the Pacific. (From World Meteorological Organization-1956)

147 E. V. KOMAREK, SR. for example, may have good conductivity while the sap apparently has little effect on conductivity. Plummer (1912) reported studies of the Dendrological Labora­ tories of the U. S.. Forest Service on wood samples of many species which showed that electric conductivity was directly related to the moisture in the wood samples. However German investigators, par­ ticularly Jonescu (Sarauer, 1922), . . . found that the electric spark struck through fresh wood the more poorly, the richer it was in fatty oil. In the same plantation the beech is rarely struck by lightning, while the oak is most fre­ quently injured. A microscopic investigation showed the reason; the wood cells of beech contained oil; those of the oak were almost free of it. They stated that "fatty trees" were those in which the starch turned to oil in winter and spring. Lund (1932) suggested that electric cur­ rents continually flow along certain circuits in the tree, thus cor­ relating the living parts of the whole tree and making it a definite and continuous electrified system. Foresters and others also became interested in lightning and its effect on trees. Most of these studies indicate that there is a differ­ ential effect on different species of trees as to their susceptibility to lightning strikes. It would appear that thin barked trees such as beech are not as apt to be injured as much as thick-barked trees such as oaks or pines. However, it is apparent that trees of some species can absorb a lightning discharge without much external damage. ' LaRue (I 922) concerning lightning injury to rubber trees 10 Malaya writes: Lightning rarely manifests itself on the Para rubber tree (Hevea brasiliensis) in tearing or breaking of the trunks or branches. Usu­ ally a single branch at the top of the tree dies first. From this point the death of the branch continues downward until the trunk is reached, then the trunk dies back until the root is reached and fi­ nally the whole tree is killed. Several days elapse from the time the injury is first visible until the whole tree is dead, the progressive death of the tissues is extremely suggestive of invasion of the tree by some destructive organism. In fact, "die-back" in rubber trees was long considered a disease. The effect of lightning on a large number of crop plants has been studied. This for a long time was confused with disease or other

148 NATURAL HISTORY OF LIGHTNING pathological conditions. In most cases with such plants as tomatoes, potatoes, and cabbage, very little external damage, such as scorching, is noted on the plants themselves. They suddenly begin to wilt and gradually die, usually in an area progressing outwards from where the lightning hit, and this is of much more common occurrence than is generally believed. In fact, experimental plots of such crops have actually been hit by lightning on experiment station grounds. In Ceylon, tea plantations are likewise damaged by lightning, and here again such damage was originally considered a disease. Here too, lightning strikes without apparent damage such as blasting or scorch­ ing. Hader (1956) writes: Lightning frequently strikes small areas of tea and kills the bushes, the roots of which are then very liable to root disease whilst at the same time there appears to be an upset in the soil micro-flora. After lightning the dead bushes should be up-rooted and the area planted with a leguminous crop. Tea may be re­ planted after a year. There are repeated references in the literature that tea bushes will die if replanted in such areas immediately. In tea orchards the shade tree Grevilleas are interplanted. These likewise are affected by light­ ning but at a much slower rate, the tea bushes dying out first. The symptoms however are very similar. For years bud-rot in coconut plantations was considered a disease and is now called false bud-rot and is due to lightning damage. Sharples (1933) states that in Malaya "the primary initiating cause of bud-rot of the coconut palm is injury by lightning." In this species the bud of the tree begins to gradually die after being hit by lightning without any external evidences of lightning damage. He goes on to say: The typical cases, locally known as budrot due to lightning strike, show a group of 10-12 trees, of which one, two or three die rap­ idly; on examination the bud tissues are found to be in a badly decayed condition. The surrounding trees show disease symptoms of varying intensity; . . . The large areas of affected palms, groups in which over 100 diseased palms may be found, are of rare occurrence. He points out that after the lightning strike the tree is quickly in­ vaded by the boring beetle, Saprosites pygmaeus, bud rot disease

149 E. V. KOMAREK, SR. Phytophthora sp., root disease Ganoderma lucidum and the stem bleeding disease Thiealaviopsis. That the same sort of effect may be occurring in our cabbage palm trees (Sabal palmetto) is indicated by the following interesting note given me by Mr. H. C. Peeples, Fire Control Chief, Florida Forest Service:

In the summer of 1952 a fire occurred after a lightning storm on a protected area in Hendry county. The ranger, Russel Hill, know­ ing that no person was in the area and not being able to find a struck tree made a further investigation later. About a week later he noted that a cabbage palm was wilting. He cut it down and found that lightning had apparently gone down inside the tree, then thru the sandy soil some several feet and then had ap­ parently ignited the fire in a clump of palmetto bushes which con­ tained much flammable material. Where the discharge went through the soil it fused some of the sand. Such fused sand tubes called fulgurites are found in a great many places over the world and in some areas in great abundance. Schonland (1950) writes in his Flight of the Thunderbolts:

In one sand-dune patch of 5,000 acres at Witsands, on the south­ eastern border of the Kalahari Desert, Lewis estimated that there were not less than 2,000 fulgurites. Since lightning is at the present time very infrequent in this area, some of these tubes must have been formed many thousands of years ago. . It is of interest that some of the fulgurites from the Kalahari Desert show fairly definite evidence that the discharge in these cases followed the roots of bushes and plants growing in the sand. The shattering effect of lightning on forest trees is well known but the details of how,' why, where and when are not. In fact, little in­ vestigation has been made into the effect of lightning on trees where such spectacular effects have not occurred. From personal observa­ tion in the Southeast, I am of the opinion that there is much more damage to forest trees than at first might seem apparent, even from the large number of trees that are known to be killed by lightning, and that the "scatter effect" mentioned in connection with the coco­ nut plantations is also of common occurrence among forest trees. The tree or trees where the direct bolt hits are of course much in evidence. What is not always apparent, except by day to day study over a

150 NATURAL HISTORY OF LIGHTNING period of time, is that the electrical discharge has weakened the sur­ rounding trees so that they in turn become ravaged by several species of pine beetles. In fact, lightning and its effect on trees might be an important environmental factor in the natural populations of these insects. Likewise, the vegetation around the base of such struck trees is also profoundly affected-sometimes for a radius of more than fifty feet. The effect of the charge on the forbs and grasses appears to be some­ what selective; that is, certain species such as bracken fern (Pteridium aquilinum) die within a few days while runner oak (Quercus minima) has appeared to be unaffected. The igniting of trees and grasses and then consequently the firing of the forest or grassland has been well documented and a few such examples are here given. Fobes (1944) has written about such examples in the forest of Maine: In most cases the lightning strikes an old stump or tree stub, the wood of which is so punky that the fire does not break into a flame but smolders. Furthermore, the precipitation from the pass­ ing storm often adds to the moisture content of the stump which is in condition to absorb water readily. This slowly burning fire is difficult to locate because the amount of smoke is not sufficient to rise above the forest canopy in large volumes and is seen only in­ termittently by the lookout men. Many hours of search are neces­ sary to determine the exact location of the fire. The area burned is usually less than a quarter of an acre. However, there is a po­ tential hazard that may become serious when the area begins to dry, particularly if the fire goes underground, where it can travel many feet to favorable fuel. Chapman (1950) writes in connection with the longleaf pine for- ests of the Southeast: How do lightning fires start in the longleaf forest? In several re­ cent instances of which careful record was made by observers, it was found that the trees struck for the most part were alive, which merely indicates that live trees constituted the most numer­ ous targets. In one instance recorded, the lightning storm was ac­ companied by a very light rain, and fires spread rapidly. Figures 8-9-10 show such actual examples in these forests. Lightning fires are also common in the coastal marshes of the South

151 Fig. 8. Tree hit by lightning and set afire June 24, 1963 Fig. 9. Close-up of same tree in Fig. 8. A drizzling rain on Greenwood Plantation. The bole of this relatively young was still falling when these photographs were made. longleaf pine had a decayed center which was combustible. Photo by Roy Komarek. The area around the tree had been control burned less than four months previously and would not carry fire even in dry weather. Photo by Roy Komarek. Fig. 10. Woods fire from lightning struck tree. The fire started at the base of the tree in grass and pine needles. Reported from Madison County, Flor­ ida Fire Report No. 21, April 21, 1960. Photo by Florida Forest Service.

being caused by direct strikes in the marshes as well as on the small islands so common to these regions. Figure 11 shows such a small pine island on the St. Marks Wildlife Refuge in Florida that was set afire by lightning on August 7, 1962. This was suppressed by refuge control crews and then the marshland around this island was con­ trolled burned for geese the following fall. Mr. Larry Requa, Fire Control Officer, Yukon Forest Service has informed me that lightning strikes in the tundra will set fire to peat and compressed moss accumulations. These may burn and smoulder for a long time, even months, and then suddenly develop into a tundra fire. Special type fire fighting nozzles have been developed for use in fighting fire underground. Mr. Henry A. Hanson, Supervisor, Waterfowl Investigations, Bu­ reau of Sport Fisheries and Wildlife, Juneau, Alaska (1963) has written me as follows and has furnished the photos of tundra fires (Fig. 12-13): The lightning-strike fire you referred to was in upland tundra at the 1000 ft. level about 35 miles north of Tanana, Alaska-July 15, 1957. I was flying from the coast near Kotzebue into Fairbanks about 500 ft. above the ground. Visibility was very poor with smoke from many forest and tundra fires. I was flying along the

153 Fig. 11. Along the Gulf Coast marshlands of Florida, lightning strikes are of com­ mon occurrence. This photo shows a small pine island on Saint Marks Wildlife Ref­ uge, typical of those that occur throughout the coastal area, that was hit by light­ ning on August 7, 1962 and set afire. The fire was suppressed by refuge control crews and the marshland around the island was control burned for geese the follow­ ing fall. Photo by E. V. Komarek, Sr.

ridge on the north side of a shallow valley about 6: 30 pm when a bolt of lightning .hit the ridge on the southside off my right wing tip. A small mushroom of dust or smoke exploded out of the dry tundra followed by flames where the lightning struck. The en­ closed photo (fig. 13) is another tundra fire burning on June 3, 1948 about 60 miles S.E. of Selawik, lat. 66 degrees 30 minutes long. 159 degrees 30 minutes. I shot the picture from an altitude of about 1000'. The fire had been burning for no more than 48 hours when I discovered it during an operational waterfowl popu­ lation survey. Apparently a fire travels quite rapidly even on a relatively flat, treeless terrain. Project "Skyfire" a most thorough study of lightning and lightning fires in the northwestern part of the United States is now going on and Mr. Arnold's excellent report has only been able to touch upon parts of it because of the limitations of time (Fuquay 1962). There are a great many eye-witness accounts of lightning caused fires throughout the United States in many of the issues of American Forests, the journal of the American Forestry Association-too many to enumerate here. There are likewise many such accounts in the fire records, of both the original fire reports by the personnel concerned directly with the fire, as well as in the published statistics of such agencies as the U. S.

154 Fig. 12. Tundra fire 35 miles north of Tanana, Alaska started by lightning July 15, 1957. Photo by H. C. Hansen, U. S. Fish and Wildlife Service.

Fig. l3. Tundra fire no more than 48 hours old southeast of Selawik, Alaska June 3, 1948. Photo by H. C. Hansen, U. S. Fish and Wildlife Service. E. V. KOMAREK, SR. Forest Service, U. S. Fish and Wildlife Service, National Park Service, U. S. Bureau of Land Management, and U. S. Bureau of Indian Affairs, and in the reports of the many state forest and wildlife agen­ cies concerned with the protection of forest and grassland. Likewise the Canadian counterparts of these agencies have full reports on fires. (Komarek 1962). There has been much discussion, largely in ethnological or anthro­ pologicalliterature, on fire in grasslands with little if any comment on the natural fires caused there-in by lightning. Much of our grasslands have either been plowed up and put into crops or overgrazed to the extent that such natural phenomena have been obscured. However, there are many such observations in the fire records of the several National Grasslands as well as in the grasslands of some of our na­ tional forests and parks. As an example, Figure 14 shows the fire data from the Laramie Peak Division at Douglas, Wyoming. This is also the headquarters for the Thunder Basin National Grassland, and the original fire reports show a great many observations on fires caused by lightning in grasslands. The following is taken directly from such a fire report on the Rabon Fire, August 21, 1960 by Dis­ trict Ranger Chas. W. Stavely and is typical of such fires: Some weather records have been furnished which indicate a build up ()f drouth preceding the occurrence of the fire. . . . 'This fire was a little east of north from De Haven. The fire fighting advantage was that there was no timber. The pastures were over-grazed and they were easy of access. In some places there appears not to be enough vegetation to carry fire. It burned none the less, and crossed barriers that would ordinarily stop it. This fire typifies what may be expected from a dry lightning a term in this short-grass area under a given set of circumstances. The personnel at the Douglas, Wyoming office as well as at Chadron, Nebraska (headquarters for Oglala National Grassland and the Nebraska Grasslands south of Nenzel) were all of the opinion that lightning is of even greater importance as an ignitor of grasslands than their records would indicate. Pastures are heavily grazed in the summer months and stockmen put out most of the fires themselves wherever possible before calling on Forest Service personnel. That lightning is quite prevalent throughout the Midwest even though the natural grasslands are no longer there is very evident by

156 NATURAL HISTORY OF LIGHTNING

no fir es -!Jl----- caused b [] man • lightning

-1JL----

aug Fig. 14. Graph showing relationship and occurrence of lightning and man-caused fires, primarily in grasslands. Data (1960) from Laramie Peak Division, Medicine Bow National Forest and Thunder Basin National Grasslands, Douglas, Wyoming. the chart (Fig 15) by the Lightning Protection Institute, Chicago, Illinois. One of the most thorough and most documented research papers on lightning fires is "Forest Fires in Alaska," by Charles E. Hardy and James W. Franks, U. S. Forest Service Research Paper Int-5 which should be studied by anyone interested in this or related sub­ jects. In Chapter 6, Fire Statistics, they write: Ideas about the general cause of fires in Interior Alaska have gradually changed. Heintzleman (1936) stated, "Fires in Alaska are almost wholly man-caused (lightning being a negligible factor) ... Also, the Alaska Fire Control Service Annual Report for 1940 stated that there were no lightning-caused fires in Interior Alaska (Robinson 1960). Evidence now on hand shows that these state,

157 E. V. KOMAREK, SR.

BARNS STRUCK BY LIGHTNING 1961 V962 by month

1_

~ ~ II"- .. A I.r.....• 1:-I~ ...,_~- .- lI- it• _ t.-'l1ill 'i 300 19(1 f \I. E \i \~ . ,. -\ j I E 1.,"61 150 : \\.Jj l • ~ Ir lJ t.. _. .,11 ""''' ii, 0 li .. >- 0 Q. U C .0 .. CI c .. > CI Q. ~ U 0 .2. -• e CI E .-~ :a CI •... 0 C ."• FIG. 15. Chart (for a section of the Midwest) from the Lightning Protection In­ stitute, Chicago, Illinois.

ments were in error; they were made before there was any or­ ganized fire protection force or even reporting procedure. Fires that actually were started by lightning were attributed to trappers, miners, and natives. One-fourth of all fires between 1950 and 1958 were reported as lightning-caused, and they accounted for three­ fourths of the total acreage burned. (italics mine) They point out that: Eighty percent of all lightning fires occur in June and July; but 73 percent of the acreage burned by these lightning fires is burned in June. Fifty-seven percent of man-caused fires occur in May. They state that the rate of fire spread or flammability of tundra is even greater than that of grasslands and that: Seventy-four percent of all fires in Interior Alaska burn in the highly flammable spruce and tundra types. The final size of a light-

158 NATURAL HISTORY OF LIGHTNING

ning fire averages 10 times the size of a man-caused fire primarily because lightning fires are common in the Interior Basin. . . . Most man caused fires occur near population centers, as would be expected. More than a usual number of reported lightning fires also burn in a somewhat similar pattern; the distribution will no doubt appear different when better detection and reporting proce­ dures are developed. They also report lightning fires occur in areas where present infor­ mation indicates a low frequency of lightning, so that lightning fires are not necessarily correlated with the frequency of thunderstorm data. Figures 16-17-18 are reproduced from this excellent paper and are typical of the kind of information the report contains. A series of fine maps showing lightning fire frequency are also included in their paper. Bennett (1960) reported upon lightning fires throughout Canada from Newfoundland to British Columbia and the Yukon. On a series of maps he plotted over 10,000 such fires in his "Survey of Lightning Occurrences in Canada's Forests-1950-1959. These maps show that although there is an apparent difference of frequency in such fires geographically, there seem to be no regions of any size free from them. The large areas where there are no records consist of the heavily settled parts of Canada and these are not under forest fire pro­ tection reporting facilities. Mr. R. H. Kendall, Supt. of Forestry, Fort Smith, Northwest Ter- ritories has written me (I 96 3) : In 1960, lightning caused 72 fires throughout the MacKenzie dis­ trict, in 1961; 96, and in 1962; 38, equivalent to 75%,59%,43% of the total number of fires caused by all causes respectively. The fires thus started spread throughout all types of vegetation. Rec­ ords show several fires of over 100,000 acres over a period of years .... Fobes (1944) reports the following in regard to lightning fires in the forests of Maine: The number of lightning fires varied from a maximum of 45 in 1937 to a minimum of 2 in 1928. The average for the 15 year pe­ riod was 18.3 fires per year, or 15 percent of the total fires from all causes. The greatest number of fires reported in a single day was 13 on September 2, 1937. All of these were the result of a severe electri-

159 E. V. KOMAREK, SR.

ACREAGE SURNfO BY MONTH LIGHTNIN5 ANO MAN-CAUSED FlIlES AVERAGE 19S()-1958

£eJel1d AREA BURNE/) --LIGHTNING FIRES 550 -- -IMN-cAUSEP FIRES J ~TOrAI. !'IRES II ~ ()F AREA 8VRNe/) 1/ D LI(fIlTNINtf FIRES o MAN-CAUSEIJ FIRES I t::::l T()TAL FIRES I II I ~ I' \1 ~\

100 1/ ./'\ \\ II \ l \ '\ \ "..-'~ ..... , Y - ...... '"'-

Fig. 16. This chart is reproduced from Forest Fires in Alaska by Charles E. Hardy and James W. Franks, U. S. Forest Service Research Paper INT-5, 1963.

160 NATURAL HISTORY OF LIGHTNING

NUM13ER OF FIRES AVERAGE 1950 - 1958

Lesen~------~ II ~ IIi-M IU.M All A6£NI:1t'S A~ASK'" OTHUn:4TEf OTNEIlSTArES

6t 22t ~005

t.t 4.6 f68.0 FIRES PER MIU.ION t92 4f9 91,848 ACRES PROTECTED

Fig. 17. This chart is reproduced from Forest Fires in Alaska by Charles E. Hardv and James W. Franks, U. S. Forest Service Research Paper INT-5, 1963. .

161 E. V. KOMAREK, SR.

NIIMBE/? AIEA BURNED 200 I------l 900r-----~

"Sr------~~~--~ ~ 800 I---fh-----; « ISO I------fi ~mol--~'~-----; ~ 600 1-----.0'1:::-----; l.a...J 126 I------~~"'" ~ ~ $00 r----'-I!.'fJ----~ ~/OO ~ 400 l---"fi1f------l ~7S I----,~~--~~~~~~-~ ;g 300 r-~'(f---~ ~~ I----~~-~~~~*-~ ~ 200 r--I.~~'1-~-~ 25 1---r-~~-~9,'w~~-~ '" 100 ~--"if-~f--_l

LI&IfTNINf9 . : :: : :, :. r:

MAN-CAV5'EP

P£RCENTA

Fig. 18. This chart if reproduced from Forest Fires in Alaska by Charles E. Hardy and James W.Franks, U. S. Forest Service Research Paper INT-5, 1963.

cal storm that passed over Washington and Hancock counties. (23 lightning fires occurred in two days) In 1927 Dr. R. Mitsuda reported in a Lightning Survey in Japan (General Electric Review, March, 192 7) on more than 2500 re­ corded lightning strikes during four years from 1921 to 1924. He

162 NATURAL HISTORY OF LIGHTNING shows the geographical distribution as well as frequency of these strokes and writes: Geographical Distribution The lightning spots are scattered according to local conditions, be­ ing dense in the K wanto district in the vicinity of Tokyo, in the Kinki district which is the middle part of the country, and in the northern part of Kiushu. [Fig. 19]. Frequency of Lightning Strokes The frequency of lightning strokes in a district may be compared to those of other districts by means of percentage representation, and the average frequency or density may be chosen conveniently as the basis of comparison or hundred percent, which really corresponds to one case of lightning stroke per 480 square kilome­ ters (approximate) of area per year. Fig. 2 [Fig. 20] shows the lightning frequencies of local dis­ tricts, laid out from the standpoint of lightning densities. Intensity of Lightning Strokes . . . the more frequent the lightning strokes are in any district, the more intense they are. In other words, the intensity is directly proportional to the frequency. Routes of Lightning Lightning stonns depend as much on the local topographical conditions as they do on the atmospheric conditions. In so far as these conditions do not differ materially, and are repeated from year to year, lightning storms will naturally have the same definite characteristics each year. Where the topographical variations are conspicuous, as in the K wanto district, the lightning characteristics are most settled and are inherent to that locality . . . It is very interesting to note that the routes of lightning storms follow the valleys from among the mountains of high altitude down to the plains. Seasonal Changes of Lightning ... lightning strokes are most frequent, irrespective of objec­ tives, in August, amounting during that month to 41 percent of the total for the year, and are next in order of frequency in July and in September, amounting to 24 percent and 14 percent of the total respectively. Through the helpful interest and cooperation of the Florida Forest Service we have been furnished with IBM records of all of their re-

163 E. V. KOMAREK, SR.

0. c ;~ orr ". ..0

Fig. 1. Geographical Distribution of Lightning Strokes in Japan

Fig. 19. Geographical distribution of lightning strokes in Japan. Reproduced from Lightning Survey in Japan, Mitsuda, 1927. ported lightning fires in their protection districts, access to the original fire reports, and other interesting and valuable data for 1963 and 1964. In particular I wish to thank -Messrs. C. H. Coulter, Forester, John Bethea, Associate Forester, and H. C. Peeples, Assistant Chief Fire Control of the Florida Forest Service for their valuable assistance and their patience for my many requests which they so willingly filled. Before discussing the data in detail I would like to point out that the Florida Forest Service in common with the U. S. Forest Service, other State Forest Services, and Canadian and Provincial

164 NATURAL HISTORY OF LIGHTNING

g More then 200" Le5~ than 200" ~ More than 100% Le55 than 100% B MOre than .50" mLes,t.han SO" 0 Unc.e.rtain

" 9 '. Fig. 2. Comparative Frequency of Lightning Strokes in Different Districts of Japan Fig. 20. Lightning frequency in local districts in Japan from the standpoint of lightning densities. Reproduced from Lightning Survey in Japan, Mitsuda, 1927.

Forestry Offices define a lightning caused fire as a fire where men and equipment have had to be used to extinguish it. Such fires are not listed as lightning fires unless there is reasonable proof that a lightning strike actually was the cause of ignition. If two or more lightning fires come together before prote<;:tive action takes place the fires are considered only as one lightning caused fire. These records on Florida lightning caused fires comprise data on 1146 reported lightning fires in 1962 and of 1048 in 1963. The data

165 E. V. KOMAREK, SR. do not include, for the present, information on such fires in Florida National Forests and the St. Marks Refuge furnished us by these agencies for fear of duplication. These will however in time be dou­ ble checked and included in our data at the Tall Timbers Station at a later date. You will note by the map of Florida (Fig. 21) that there appear to be certain patterns evident. These are not necessarily patterns of light­ ning occurrence locally for lightning fires cannot start unless there is

Fig. 21. Lightning caused fires in Florida during 1962. Data from Florida Forest Service.

166 NATURAL HISTORY OF LIGHTNING fuel upon which they can feed. Thus you will note that in Leon and Jefferson counties there are many records of lightning fires south of Tallahassee and virtually none to the north. The region in the north­ ern part of these counties consist of hunting plantations where an annual rotation of burning is practiced. It also appears that there are fewer lightning fires on the Apalachicola National Forest, though this is subject to further check, where much of the forest land is on a three-year rotation or there-abouts. Wherever wiregrass predomi­ nates, and it occurs ov~r much of the forest in the deep south, even a three-year "rough" will burn very readily from a lightning fire but is not as easily ignited as say a "20 year rough." It would also appear from some preliminary data that as the length of fire exclusion increases the incidence of lightning fires increases at a much more rapid ratio. The chart (Fig. 22) of Levy county where protection was first established in 1954 shows this quite clearly. In Florida, the man-caused fires occur largely in the winter months whereas the lightning ignited fires are ne:lrly all summer fires (Figs. 23,24). Though the number of fires per day are different the pattern seems to be the same-that is late May, June, July are the months when most such fires are started. This ties in quite nicely with what we know of the "thunderstorm days" and other such data of this same region (Fig. 24). That lightning is a major element in forest or grassland fires is now an accepted fact by most foresters. However, it is not always so gen­ erally known as to how great such a factor exists. Such a lightning factor however does exist world-wide in nearly all vegetative types where there is enough fuel to burn. If the area is being burned by man, either by controlled burning or wildfire, or if the area is being intensively pastured, cultivated, or built up, lightning fires cannot de­ velop. But the lightning potential is always there. Insurance people writing in the Eastern Underwriter Journal say:

Lightning will start fires on 30,000 American farms this year. It will kill one American every day, injure four others, and frighten thousands more. No crystal ball is needed to make these predic­ tions. These figures are averages of what has occurred in recent years and what can be expected in 1953.

167 E. V. KOMAREK, SR. 300 FIRES IN LEVY COUNTY 1954·1963

200 man-caused fires lightning-caused firos---·

100

I I ", It.... ,', ,~... I / --~ '-...... ,,; ' -~ • I , I , • I • • I 54 55 56 57 58 59 60 61 62 63 Fig. 22. Fires in Levy County, Florida, 1954-1963.

Lightning continues to be the greatest single cause of farm and rural fires. Fire underwriters state that lightning causes 37 out of every 100 such fires, exacting a $35,000,000 toll, year after year, on farms alone. No figures are available for the unreported or unin­ sured losses . . . The National Board of Fire Underwriters has reported under Leading Causes of Fire in U. S. 1953-1961 (The World Almanac- 1964) that out of a total of 2,022,672 reported fires, 243,276 or 12% of the total were caused by lightning. These totals are for reported fires where the cause was ascertained and do not represent either the total number of fires or the total property loss in the United States. Excluded are all unreported losses as well as all fires with cause of ignition unknown.

168 NATURAL HISTORY OF LIGHTNING

Fig. 23. A comparison of lightning and man-made forest fires in Florida during the years 1962 and 1963.

169 E. V. KOMAREK, SR.

30 00 • lightning fires

D thunderstorm days

20u------~------'200

1ou------~~~h4~~------100

feb mar apr may J un j uI aug .so poet nov Fig. 24. Correlation of lightning fire from Florida Forest Service data with "thunderstorm days" reported from eight U. S. Weather Bureau stations in pro­ tected Florida forest area.

With all the data that has been presented there should be no ques­ tion as to the magnitude of lightning in the environment of plants and animals. In fact lightning may have also been responsible for the evolution of life itself from inorganic materials, at least according to certain theories now prevalent. Oparin (1938) suggested that in the earliest beginnings on earth that the constant striking of lightning on the "primordial soup" of the oceans may have started what we call life. Urey (1952) later enlarged upon this thesis and Miller in 1945 produced some 25 or more amino acids and other organic compounds, the building blocks of living matter so to speak, by the constant bom­ bardment of such an experimental "primordial soup" with "artificial" lightning. It is a truism in ecological thought that any environmental force acting upon living matter, plants or animals, by a process of natural selection, will cause those genes to be selected out of the germ plasm or "gene banks" that will best allow that living matter to succeed in a struggle for existence. Not only has lightning developed fire adap­ tations, or as most geneticists would prefer, selected out those "pre-

170 NATURAL HISTORY OF LIGHTNING adaptations" for the most succe.ssful existence with conditions created by fires; but also that plants at least have developed similarly in regard to lightning itself. This is to say, that the reaction to the lightning stroke and attendant conditions are different in different vegetations. Plants, animals, and possibly life itself, have evolved through a long process of natural selection in an environment where lightning and fires so initiated have been an important factor, more important than many ecologists may realize. Today, in many regions lightning ignited fires are the primary cause of forest and grassland fires; in other areas increased and more effective fire protection has created conditions whereby, percentage wise at least, lightning fires are beginning to become quite a problem.

CONCLUSION The natural history of lightning wherever studied has shown a preponderance of evidence that: 1. Lightning is an inherent component of the earth's atmosphere and is ecologically fully as important as such better known factors as temperature, rainfall, soils, etc. 2. Although plants and perhaps some animals show a differential re­ sponse to the electrical charge we call lightning it is of greatest importance in the environment as the causative agent of natural fires (as differentiated from man-caused). 3. Lightning is of suc!). frequency and magnitude that there are not many lands, if any on earth, that at some time or other have not been subjected to re-occurring lightning caused fires. These have occurred at frequent enough intervals to have lasting effect on plant and animal communities. 4. Plant and animal communities have evolved largely as the effect of summer fires. 5. The effect of such an environmental agent as lightning has long been obscured because of man's activities and use of fire. It is im­ portant to note that although in the far north man-caused fires occur nearly at the same time of year as lightning-caused fires, this is not so in more temperate and sub-tropical climates where man­ caused fires occur mainly in late fall, winter, or early spring and the lightning caused fires develop in the summer months.

171 E. v. KOMAREK, SR. 6. Lightning as an environmental factor was on earth long before the evolution of man. The antiquity of fire seems apparent in that the most ancient of tree families, such as the conifers, and the appar­ ently oldest genera of grasses, such as Aristida, Stipa, Andropogon, etc., have the greatest concentration of those genes responsible for resistance and adjustment to a "fire environment." In fact, it ap­ pears that during long periods of time fire type communities of plants and animals have covered vast areas of the earth's land surface. 7. The evidence accumulated since our first fire ecology conference continues to substantiate the following concept then expressed: In nature, fire is a great regenerative force, one might even say rejuvenative force, without which plant and animal succession, in the absence of climatic upheaval or physiographic cataclysm (or at least of great climatic or physiographic change), would be re­ tarded so that old, senescent, and decadent communities would cover the earth (Komarek 1962).

BIBLIOGRAPHY

This is by no means a complete bibliography on lightning but only represents material consulted in preparation of this paper. Beginning about a half century ago, with the wide-spread use of electrical power and the necessary distribution lines over various parts of the globe a very large literature has developed in regard to lightning and its effect on these power distribution installations. There are well over 2000 such titles. The American Institute of Electrical Engineers Library in New York is trying to maintain relatively current bibliographies in this field. The. material on lightning of primary interest to biologists, however, is scattered throughout many journals (including the field of electrical engineering), books, and other publications and only rarely is indexed. Much of this material is of consider­ able value for a proper understanding of the ecological aspects of lightning. We would appreciate from interested readers, any references not included in the present bibliography for we will continue to gather such information as time will permit. The writer wishes to acknowledge the interest and valuable help furnished him by the librarians of the Robert Dozier Library of Florida Slate University, National Agricultural Library, Library of Congress, Library of the American Institute of Electrical Engineers, Illinois Institute of Technology, and by the Georgia Coastal Plains Experiment Station Library, Tifton, Georgia. Adam, D. B. 1938. The injury of grapevines by lightning strike. J. Australian Inst. Agr. Sci. 4: 162-164. Albright, J. G 1937a. A lightning flash and its component strokes. J. Applied Physics 8:313-18.

172 NATURAL HISTORY OF LIGHTNING

1937b. Apparatus for photographing lightning flashes. Review of Scientific Instruments 8: 36-37. Allard, H. A. 1936. Remarkable lighming bolt. Science 8: 136-137. American Institute of Electrical Engineers. 1950. Lightning Reference Bibliography 1936-1949. --.1962. Lighming Reference Bibliography 1950-1960. Anderson, A. E. 1925. Sand fulgurites from Nebraska-their structure and formative factors. The Neb. State Mus. Bull. 1 (7). Anderson, R. B., and R. D. Jenner. 1954. A summary of eight years of lightning in­ vestigation in Southern Rhodesia. Trans. South Africa lEE Part 7, 45:215-241; Part 9, 45:261-294. Anonymous. 1924. Trees and lightning stroke. Rural New York 83:1499. --. 1931. Tea Research Institute of Ceylon Bull. 8. --. 1936. Lightning discharge research in South Africa. Trans. South African Inst. Electrical Engineers 27: 158. --. 1939. Some beliefs about lightning and trees. Garden Digest 11:24-6, Illustra- tions from "Beautiful Shade Trees." The Davey Tree Expert Co. --.1941. Lighming and trees. Flower Grower 28:375. --. 1942a. Trees lighming does not strike. Garden Digest 14:78. --. 1942b. Lighming fertilizes soil. American Fertilizer 96:20+. --.1944. "Klydonogram" reproduced on golf green by lightning stroke. Electrical Engineering 63: 56. --. 1945. Lighming functions as nitrogen fertilizer. Electrical World 123 :99. -~. 1952. Thunderbolts: The Electric phenomena of thunderstorms (discussions). Nature 169(4301) :561-563. --. 1953a. Lighming is expected to cause 30,000 farm fires during 1953. Eastern Underwriter (succeed J. Ins. Eco.) 54:25. --. 1953b. Loss ofrnillions from lightning. Am. Poultry J. (midwest) 84: 12. --. 1955. Protect against lightning. Am. Poultry J. (midwest) 86:26. --. 1956a. Lighming accidents. (editorial) Am. Vet. Med. Assn. J. 129:243. --. 1956b. Lighming protection. Maryland Fruit Grower 26:8+. --.1957. Project Skyfire. Agr. Res. 5:8-9. --. 1958. Sequelae of lightning stroke. Am. Vet. Med. Assn. J. 132:sup. 42 --. 1959a. Lightning a hazard in rural areas. Wallaces Farmer 84:51. --. 1959b. Lightning the destroyer. Farm Quarterly 14:54-54+. --. 1959c. Check livestock losses on pasture. Wallaces Farmer 84:72. --. 1959d. Effects of lighming awesome and costly. Am. Cattle Producer 41:29. --. 1964a. Leading causes of fire in U. S. 1953-1961. The World Almanac-New York World-Telegram. (source National Board of Fire Underwriters). p. 683. --. 1964b. Lightning and man cause many forest fires. [source: Forest Service USDA]. The World Almanac-New York World-Telegram p. 689. --. 1952. Lightning and Buildings. Statistical investigation of lightning strokes in Switzerland from 1925-1947. Bull. Assoc. Suisse. Elect. 43:428-432. [In Frenc):l]. Appel, O. 1907. Lightning in potatoes. (from Jones and Gilbert). Mitte a de Kaiserl. BioI. Anst. f. Land, U. Forstw. 5:19. Augur, H. 1946. Zapotec. Garden City, N. Y. Barbour, E. H. 1925. Notes on Nebraska fulgurites. The Neb. State Mus. Bull 1 (6). Barrows, J. S. 1954. Lighming fire research in the Rocky Mountains. J. Forestry 52:845-847. --, Vincent J. Schaefer, and Paul B. MacCready. 1954. Project Skyfire, a progress report on lighming fire and atmospheric research. Research Paper 35, Inter­ mountain. Forest and Range Expt. Sta. --. 1956. The Skyfire cloud survey. Paper presented at 143rd National meeting, A.M.S., New York City.

173 E. V. KOMAREK, SR.

--.1958. Project Skyfire. Final Report of the advisory committee on weather con­ trol Vol. II. Washington, D. C. ---. 1960. Control of lightning fires in American forests. Proc. Fifth World For­ estry Congress 2:851-856. ---. 1962. 1962 status and activities of Forest Fire Research Laboratories. Proc. Ann. Meet. Western Forest Fire Res. Comm., Western Forest and Consv. Assoc., Seattle, Washington. ---. 1963a. Fire weather aspects of research at the Northern Forest Fire Labora­ tory. 1963 West. Fire Weather Meteorol. Conf., Portland, Ore .. 15 pages. [No reprintsl. --. 1963b. Forest fire science. Naturalist 14(4): 18-25, illus. [No reprintsl. Baxter, L. F. 1956. Lightning demolishes hive of bees. Gleanings (bee) 84:560. Bear, Firman E. 1929. Theory and practice in the use of fertilizers. Wiley. pp. 10, 60. Beard, F. H. 1946. Annual Report. East MaIling Res. Sta. Kent, England, Chpt. VIII on Hops, 1945, pp. 41-43. Bell, R. 1897. The geographical distribution of forest trees in Canada (with map). Reprinted from The Scottish Geographical Magazine for June. 1897. Bellaschi, P. L. 1939. Lightning strokes in field and laboratory. Electrical Engineer­ ing 58:466-468. Bennett, W. D. 1958. The control of lightning-caused forest fires. Pulp and Paper Res. Inst. of Canada. Woodlands Research Index 106. --. 1960. Survey of lightning fire occurrences in Canada's forests. -1950 to 1959. Pulp and Paper Res. Inst. of Canada. Woodlands Research Index 120. Berger, K. 1946. Swiss lightning research on Monte San Salvatore, near Lugano. (in French). Bull. Assoc. Suisse des Electriciens 37:319-326. Biswell, H. H. 1963. Research in wildland fire ecology in California. Proc. Second Ann. Tall Timbers Fire Ecol. Conf. pp. 62-97. Tall Timbers Res. Sta. Bower, S. Morris. 1950. Recent work of the thunderstorm census organization. Quart. J. Meteorol. Soc. 76:455-478. Brown, H. D., and M. W. Gardner. 1923. Lightning injury to tomatoes. Phyto. 13:147. Browne, I. C., H. P. Palmer and T. W. Wormell. 1954. The physics of rainclouds. Quart. J. Roy. Meteorol. Soc. (London). 80:291-327. Brook, M., and N. Kitagawa. 1960. Some aspects of lightning activity and related meteorological conditions. J. Geophys. Res. 65:1203-1210. Brooks, C. F. 1922. The local, or heat, thunderstorm. Monthly Weather Review 50(6) :281-287. Bruce, C. E. R., and R. H. Golde. 1941. The lightning discharge. J. Instimtion of Electrical Engineers II, 88:487-505. ---. 1958. Terrestrial and cosmic lightning discharges. Rept. British Elec. Res. Assoc., ZlT119, 8 pages. --. 1959. Cosmic thunderstorms. J. Franklin Inst. 268:425-445. Bumstead, A. P. 1943. Sunspots and lightning fires. J. Forestry 41:69-70. Burr, H. S. 1956. Effect of a severe storm on electric properties of a tree and the earth. Science 124: 1204-1205. Burr, S. 1933. Lightning damage to potatoes. Garden Chron. 94:48. Busgen, M. 1929. The strucmre and life of forest trees. (3rd edition-by E. Munch) (translated by Thomas Thomson) New York. Byers, H. R. 1949. Strucmre and dynamics of the thunderstorm. Science 110:291-294. --. 1950. Suggestions and plans for future work in thunderstorm electricity. Rept. Thunderstorm Elec. Conf., Univ. Chicago, Dept. Meteorol. ---, and H. R. Rodebush. 1948. Causes of thunderstorms of the Florida peninsula. J. Meteorol. 5(6). --, and R. R. Braham. 1948. Thunderstorm structure and circulation. J. Meteorol. 5 (3) :71-86.

174 NATURAL HISTORY OF LIGHTNING

Calvin, M. 1956. Chemical evolution and the origin of life. Am. Scientist. 44:248-263. --. 1959. Evolution of enzymes and the photosynthetic apparatus. Science 130: 1170-1174. Chalmers, J. A. 1951. The origin of the electric charge on rain. Quart. J. Roy. Meteorol. Soc. 77:249-259. Chapman, H. H. 1950. Lightning in the longleaf. J. Am. Forestry 56:10-11+. Chapman, Seville. 1949. Mechanisms of charge generation in thunderclouds (ab­ stract). Physical Review 75:1333. Clarence, N. D., and D. J. Malan. 1957. Preliminary discharge processes in lightning flashes to ground. Quart. J. Meteorol. Soc. 83: 161-172. Clark, W. G. 1937. Polar transport of auxin and electrical polarity in coleoptile of Avena. Plant Physiol. 12:737-754. Cleveland, A. 1904. Lightning on water, etc. (from Jones & Gilbert 1915). Monthly Weather Review 32:323. Colladon, D. 1872. Effets de la foudre sur les arbes it las plantes lignenses. Meme de la sec. de phys et d'histore note de Geneve. Collins, H. W. 1937. Lightning currents measured. AlEE Lightning Ref. Bk. pp. 1337-1338. (Orig. in Elec. World, May 12, 1934). Conwell, R. N., and C. L. Fortescue. 1937 Lightning Laboratory of Stillwater, New Jersey-30 to 40 lightning storms a year-6 miles from Newton. AlEE Light­ ning Ref. Bk. pp. 746-750: Cook, H. J. 1925. Manganese fulgurites. The Neb. State Mus. 1 (5). Covarrubias, Miguel. 1946. Mexico South: the Isthmus of Tehuantepic. Alfred A. Knopf, Inc., New York. Cox, H. J., and J. H. Armington. 1914. The weather and climate of Chicago. The Geographic Soc. Chicago Bull. 4. Craig, R. W. 1940. Lightning storm. Am. Forests 46:354-356+ illus. Creighton, E. F. 1937. Lightning. AIEE Lightning Ref. Bk. pp. 104-110. Davis, H. M. 1938. Multiple strokes in lightning. Science 88:593. Defandorf, F. M. 1956. Electrical resistance to the earth of a live tree. AlEE Trans. III,75:936-941. De Fonvielle, W. 1868. Thunder and lightning. London: Sampson Low, Son, and Marston, Milton House, Ludgate Hill. Dillard, E. W. 1937. Lightning investigation on New England powers systems around Amhurst, Mass., New Boston (Merrimac River). AIEE Lightning Ref. Bk. pp. 292-294. Dodge, A. W. 1936. Lightning damage to trees. Nat!. Shade Tree Conf. Proc. 43:55. Dorsey, N. E. 1937. Lightning. AIEE Lightning Ref. Bk. pp. 180-182+. Evans, E. A., and K. B. McEachron. 1936. The thunderstorm. General Electric Re­ view 398:413-425. Fenska, R. E. 1952. Your shade trees; what is your shade tree worth. Am. Forests 58:17+. Fitzgerald, O. A. 1956. Lightning still a troublemaker. Am. Forests 62:24-25+. Flowers, J. W. 1941. The direct measurement of lightning. J. Franklin Institute 232:425-450. --. 1944. Lightning. General Electric Review 47:9-15. Fobes, C. B. 1944. Lightning fires in the forests of.Maine. J. For., 42:291-293. biblio­ table. Forrest, J. S. 1950. Variations in thunderstorm severity in Great Britain. Quart. J. Meteorol. Soc. 76:277-386. Fortescue, C. L. 1937a. Slow cloud ionization confirms direct-strike theory. AlEE Lightning Ref. Bk. pp. 700-701. --. 1937b. A theory of lightning. AIEE Lightning Ref. Bk. pp. 317-320.

175 E. V. KOMAREK, SR.

--. 1937c. Lightning-Its behaviour-How it is controlled. AlEE Lightning Ref. Bk. pp. 95-100. (Orig., 1930, Elec. J. Vol. 27, Feb. 1930). Freeman, J. F. 1924. Nitrogen in the rainwater at different points in Kentucky. J. Am. Soc. Agron. 16:356-358. Frenkel, J. 1947. Atmospheric electricity and lightning. J. Franklin Institute 243:287- 307. Fritsch, Volker. 1960. Lightning risk and lightning damage in Austria. Elektrotech. u. Maschinenbau 77(4) :78-82. [In German]. Fuquay, Donald M. 1962. Project Skyfire progress report, 1958-1960 Research Paper 71, Intermountain Forest & Range Expt. Sta. U. S. Forest Service, Ogden, Utah. Gadd, C. H. 1944. Report of the Mycologist for 1944. Bull., Tea Research Inst., Ceylon, 26:23-30. Gaumann, E. 1950. Principles of plant infection. Hafner, New York, page 543. (trans. Brierley, William B. of Gaumann "Pfianzliche Infektionslehre") Georgia Forest Research Council. 1963. Lightning fires increase in state. Forest Research and Development (2) 5 pp. Gisborne, H. T. 1942. New facts on lightning. Research Note No. 20, Northern Rocky Mt. Forest Expt. Sta. USFS- mimeo. Gish, O. H. 1950. Comments on thunderstorm electricity. Rept. Conf. on Thunder­ storm elec., Chicago, April 10-13, 1950, Univ. Chicago, Dept. of Meteorol. --, and G. R. Wait. 1059. Thunderstorms and the earth's general e.lectrification. J. Geophys. Res. 55:473-484. Gleizer, M. D. 1953. Thunderstorms in central Asia. Elekt. Stantsii, No.5, pp. 42-44. (In Russian). Goodlet, B. L. 1937. Lightning. J. Inst. Electrical Engineers 81:1-26. Graham, H. E. 1960. Lightning probability forecast. July Fire Control Notes 21(3): 69-74. Grubb, N. H. 1949. Lightning damage to raspberries. East MaIling Res. Sta. Rept. 1948:81. Gunn, Ross. 1954. Electric-field regeneration in thunderstorms. J. Meteorol. 11 (2): 130-138. --. 1955. Electrification of cloud and rain drops by ionic diffusion and droplet as­ sociation. Science 121 :623-624. Hagenguth, J. H. 1940. Lightning recording instruments. General Electric Review 43:195-201; 248-255. --.1947. Photographic study of lightning. AlEE Trans. 66:577-585. Harder, E. L., and J. M. Clayton. 1951. Lightning phenomena. West. Engr.11:106-111. --, and J. M. Clayton. 1952. Properties of lightuing strokes. Electrical World 137(22) :106. Hardy, Charles E., and James W. Franks. 1963. Forest Fires in Alaska. U. S. Forest Service Research Paper Int. -5. Harler, C. R. 1956. The culture and marketing of tea. 2nd ed. Oxford Univ. Press, London. Hawkins, S. 1933. Some effects of lightning on tomato plants. Proc. Indiana Acad. Sci., 42 (1932) :57-59. Henry, A. J. 1901. Loss of life in the United States from lightning. Weather Bur. Bull. (30) :21. --. 1912. Lightning and lightning conductors. USDA Farmers Bull. 367, orig. issued 1909. Hirshberg, B. 1950. Lightning demands respect, not fear. Successful Farmer 48:60+. Holzer, R. E., E. J. Workman, and L.B. Snoddy. 1938. Photographic study of light­ ning. J. Applied Phys. 9: 134-138. --, and E. J. Workman. 1939. Photographs of unusual discharges occurring during thunderstorms. J. Applied Physics. 10:659-662.

176 NATURAL HISTORY OF LIGHTNING

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