2.7 A REVIEW OF ELECTRICAL AND TURBULENCE EFFECTS OF CONVECTIVE
STORMS ON THE OVERLYING STRATOSPHERE AND MESOSPHERE
Walter A. Lyons*
FMA Research, Inc., Fort Collins, Colorado
Russell A. Armstrong
Mission Research Corporation, Nashua, New Hampshire
According to The National Space Weather Program
(NSWP), “space weather” refers to conditions on the Sun
and in the solar wind, magnetosphere, ionosphere and
thermosphere that can influence the performance and
reliability of space-born and ground based technological
systems and can endanger human life or health (OFCM,
1997). Well documented have been the impacts of
energetic particles and geomagnetic storms on satellite
and communication systems, induced currents in the
electric power systems due to geomagnetic field
fluctuations, and space weather hazards to astronauts.
The NSWP Implementation Plan notes that the goals of
the National Space Weather Program can be achieved
only when the representation of space weather is
coupled into a seamless system, starting at the sun and
ending at the Earth. One can not dispute this notion, but
this paper suggests that a slightly broader perspective
might be in order. We note that an indirect solar
influence upon the middle atmosphere derived from
heating of the surface deserves growing attention.
Insolation warms the Earth’s surface which in turn
generates deep convection, further resulting in significant
hydrodynamic and electrodynamic disturbances
throughout much of the middle atmosphere. The impacts
of tropospheric thunderstorms are now understood to
extend through the depth of the stratosphere,
mesosphere and even into the lower ionosphere. This
region sometimes, only partly in jest, is termed the
“ignorosphere,” because its presumed quiescence and
inaccessibility has lead to a dearth of remote and in situ
measurements. Satellites and Space Shuttles overfly this
region. Sounding rockets can only obtain readings lasting
mere seconds. Costs and performance limitations limit
aircraft and balloons to brief probes of the very lowest
extremity of the region. Yet the thin atmosphere beyond
the tropopause is soon to become increasingly
populated. Proposed high altitude airships (HAAs),
including station-keeping balloons and UAVs, may be
deployed for various purposes including research,
communications and national security surveillance.
Upcoming generations of civil transports and military
aircraft will log increasing time in the atmosphere above
thunderstorms. The Space Shuttle
• Corresponding Author: Walter A. Lyons, CCM
FMA Research, Inc., Fort Collins, CO 80524,
and its successors must continue to ascend and descend
through the region. The speculation (in part fueled by the
press) about the possibility that the Shuttle Columbia was
felled by interaction with a sprite, and the considerable
effort needed to discount this as a plausible cause
(NASA JSC 2003), highlighted the limitations in our
understanding of the electrodynamics of the region
between 20 and 90 km. This paper surveys recent
research which suggests that the stratosphere, as well as
the overlying mesosphere, are neither electrically nor
dynamically “uninteresting.” Those planning to operate
HAAs within the region should be aware that what has
been heretofore presumed about the “weather” of this
region may not be necessarily always be true.
2. A CAUTIONARY TALE
During the summer of 1999, the authors were
preparing to participate in a major NASA scientific
balloon mission to study sprites above High Plains
thunderstorms (Bering et al. 2002). Sprites are the most
common middle atmospheric transient luminous event
(TLEs) induced by intense electrical activity in deep
tropospheric convective storms (Fig. 1). Lasting for a few
to tens of milliseconds, they illuminate thousands of cubic
kilometers of the atmosphere between 30 and 90 km
(Lyons et al. 2000), in a fleeting thunderstorm-induced
“aurora.” It is increasingly agreed that sprites result from
conventional electrostatic breakdown at around 70 km,
the result of intense electrical fields caused by the
removal of large amounts of electrical change from
clouds by unusual cloud-to-ground (CG) lightning
strokes. Electrical streamers extend both upward and
downward, but are generally not thought to contact the
underlying cloud tops. During the final planning stages for
the 1999 balloon missions, NASA informed the
participants that the balloons would not be allowed to
directly overfly thunderstorms. This was the result of
regulations imposed after a little-known 1989 balloon
mishap, which was ranked as the second worst “federal
disaster” of that year, behind the crash of an F-15.
On the morning of 6 June 1989, NASA launched a
nearly 30 million cubic foot research balloon from its base
in Palestine, TX. It carried a two-ton science payload (a
laser system for chemical measurements). The balloon,
as expected, reached a flight altitude of 120,000 ft (~37
km) and drifted westward. As evening approached it
began to overfly a large region of severe thunderstorms
in west Texas. The balloon then gradually descended to
110,000 ft (33.5 km) by 0038 UT 7 June 1989, about 55
miles (88km) west of Ft. Worth, TX. At that point an
uncommanded payload release occurred. The balloon,
parachute assembly, and payload descended, landing in
three different areas. The 4000 lb science payload, some
6 feet in diameter and 5 feet tall, struck the ground near
Graham, TX at an estimated speed of 600 mph, burying
itself in a small crater. Fortunately there were no injuries
or collateral property damage. Flight 1482P was declared
a failure, with a loss of $1 million in equipment and
What caused the uncommanded payload release has
been a matter of considerable conjecture and concern
ever since. Two PC cards from the flight termination
electronics page were retrieved, inspected, and found to
have suffered electrical damage and overheating. The
command strobing chip was damaged and discolored
due to electrical overstress and heating. Several pins
were found shorted together with evidence of arc-over.
The investigating committee determined the most
likely cause was “low-level high-voltage current induced
into the termination electronics package by lightning
activity present in the area.” However, it seems
improbable that activity within the storms below could
explain this incident. At the time of the failure, the balloon
was approaching thunderstorms with reported radar echo
tops to 65,000 ft (19.8 km). Even if directly above the
highest part of the storm, the balloon was fully 14 km
distant from any conventional lightning discharge within
The event occurred almost exactly a month before
the first sprite was imaged by a low level camera above a
storm system in Minnesota (Franz et al, 1990), an event
which has changed our perception of electrical
phenomena in the middle atmosphere above storms.
Discoveries since that time may shed new light on the
fate of Flight 1482P.
3. A CONNECTION TO THE IONOSPHERE
Since 1989, more than 10,000 low light television
(LLTV) images of sprites have been obtained by various
research teams (Lyons, 1996; Sentman et al. 1995;
Lyons et al., 2000, 2003a). Blue jets (Wescott et al, 1995)
and elves (Fukunishi et al. 1995) have also been
observed with a variety of sensors. While a sprite is
unlikely to have directly interacted with the balloon, the
application of theories proposing conventional dielectric
breakdown as the initiator of sprites suggests electrical
transients on the order of 103 to 104 V/m may have
occurred at flight level (Williams, 2001; Rowland, 1999).
Such transients result from rather rare and unusually
powerful lightning discharges lowering hundreds of
Coulombs of charge to ground, as detailed by Hu et al.
(2002), Lyons et al. (2003a) and others. Systems not
deigned with the potential for such transients in mind may
indeed be expected to encounter failure modes. And in
the decade since the discovery of sprites, many other
TLEs, many emanating directly from cloud tops, have
been discovered. It is certainly not out of the question
that the NASA balloon passed far closer than 14 km to an
electrical discharge, or possibly was even directly
involved in such an event.
Many anecdotal reports in the literature events
(Vaughan and Vonnegut, 1989; Lyons and Williams,
1993; Heavner, 2000; Lyons et al. 2003b) described
TLEs which can not be categorized as sprites:
“…vertical lightning bolts were extending from the tops of
the clouds…to an altitude of approximately 120,000
feet…they were generally straight compared to most
“…at least ten bolts of lightning went up a vertical blue
shaft of light that would form an instant before the
lightning bolt emerged…”
“...a beam, purple in color…then a normal lightning flash
extended upwards at this point…after which the
discharge assumed a shape similar to roots in a tree in
an inverted position…”
“…an ionized glow around an arrow-straight finger
“…an American Airlines captain…near Costa Rica…saw
from an anvil of a thunderstorm….several discharges
vertically to very high altitudes…the event was white…”
“…the top of the storm was not flat…looked like a dome
of a van de Graff generator...clearly saw several bolts of
lightning going upwards…dissipating in the clear air
above the storm…all in all 5 or 6 occurrences …”
Upward extending white channels topped by blue
flame-like features were captured on film near Darwin,
Australia (Lyons et al. 2003) and over the Indian Ocean
(Wescott et al. 2001). This latter event reached a height
of ~35 km. Welsh geographer Tudor Williams, who in
1968 was residing near Mt. Ida, Queensland, Australia,
visually observed a series of lightning-like channels rising
at least several kilometers above the top of a large
nocturnal thunderstorm. He photographed several of the
approximately 15 events (using 50 ASA 35 mm
transparency film, long exposures) that occurred at fairly
regular intervals over a 45 minute period. Figure X shows
the bright upward channel along with a hint of a faint blue
flame flaring upward and outward from its upper portion
reaching a height equal to or greater than the bright
channel. Upward-extending electrical discharges from a
supercellular thunderstorm over Colorado were observed
during the Severe Thunderstorm Electrification and
Precipitation Study (STEPS) on 22 July 2000 (Lyons et
Eyewitness recollections of many lightning-like
channels emanating from overshooting convective
domes of very active storm cells have a number of
common characteristics. They appear bright white to
yellow in color, are relatively straight, do not flicker,
extend above cloud tops to heights equal to or exceeding
the depth of the cloud (10-15 km), are notably long
lasting (~1 second) and can be observed during daylight.
It is difficult to understand how these might represent the
faint blue jet phenomenon reported by Wescott et al.,
On 15 September 2001, a team of scientists familiar
with sprites and blue jets were investigating the effects of
lightning on the ionosphere at the Aricebo Observatory in
Puerto Rico (Pasko et al., 2002). At 0325.00.872 UTC,
above a relatively small (~2500 km2) storm cell 200 km
northwest of Arecibo, the LLTV video captured an
amazing upward discharge, blue in color, one frame of
which is shown in Figure 1 (see the full animation at
http://pasko.ee.psu.edu/Nature). Clearly seen as brilliant
blue to the naked eye, it appeared as a series of upward
and outward expanding streamers which rose from the
storm top (16 km). The event reached a terminal altitude
of 70 km, the estimated lower ledge of the ionosphere.
The event lasted almost 800 ms, including several re-
brightenings. This case marks the first hard evidence of a
direct electrical link between a tropospheric thunderstorm
cell and the ionosphere. A series of five similar giant
upward jets have since been reported emanating from
thunderstorm tops over the Pacific near the Philippines
(Su et al. 2003). While sprites are believed to occur with
a global frequency of several per minute, the number of
upward jets and lightning-like discharges remains
unknown. It is becoming clear, however, that they are
less rare than once believed.
A wide variety of upward electrical discharge
phenomena occur from thunderstorm tops, many
penetrating the stratosphere and some extending through
the mesosphere. As scientific and defense platforms
expand their domain into the stratosphere, it is
imperative that the dynamic electrical nature of the region
be considered. Sprites, jets and related TLEs are also a
potential source “optical clutter” for spaceborne
monitoring and missile detection systems. To the extent
their optical signatures are not well characterized, the
potential remains for natural phenomena to be
4. VERTICAL MOTIONS AND TURBULENCE
It has now become recognized that large thunderstorm
systems can generate upward propagating gravity waves
which often amplify with height, perhaps even breaking in
the middle atmosphere (Taylor and Hapgood 1990;
Alexander et al. 1995). The large mesoscale convective
systems of the High Plains, often prolific sprite producers,
have been known to generate gravity wave trains visible
from OH airglow emissions at the ~85 km level (Sentman
et al. 2002). These waves are often bright enough to be
visible with the naked eye.
Yet this energy must first propagate through the
stratosphere, a thermally stable layer often characterized
as devoid of “weather.” The very stability which makes
this characterizations true on a global scale also can
result in significant turbulence, vertical motions and wind
shears on the scale of convective storms. Evidence is
accumulating which suggests these storm’s impacts may
extend for ten km, and maybe much more, above cloud
tops. As contemporary aircraft routinely fly around and
not over thunderstorms, little operational experience is
available documenting conditions above intense
convective storms. Occasional ER-2 missions above
deep convective storms have tended to concentrate on
optical and electrical field measurements. Similarly, high
altitude research balloon missions are not instrumented
to determine convective scale turbulence, vertical motion
and wind shears. Learjet flights investigating tornadic
storms by the late Prof. T. T, Fujita nearly three decades
ago, used photogrammetric methods to reveal the
extreme turbulence and wind shear present at the top
and above intense convective storms (Fujita, 1992).
Figure 3 shows a montage of phenomena present above
thunderstorm tops. The tropopause is not necessarily a
boundary for “weather” or even mass flux. We note Wang
(2002) has demonstrated that flow around and over deep
convection generates intense gravity wave motions which
can transport material from the storm into the
stratosphere itself. Included in Figure 3 is a scene from a
video which reveals a stratospheric cirrus plume several
kilometers above the top of a supercell storm observed
during the 2000 STEPS program. Animation makes it
clear that this plume was formed by intense gravity wave
action extending well above the storm top. Such intense
motions above storms have also been indicated by high
resolution numerical simulations of airflow around and
over convective domes penetrating into the stratosphere
(Droegemeier et al. 1997). As shown in Figure 4, such
motions can reach several meters per sec many
kilometers above the visible storm tops. Such
“tropospheric style” conditions could well pose control
issues for station keeping HAAs or UAVs operating in the
lower stratosphere unless accounted for in the design of
Research over the past decade has drawn attention
to the fact that the middle atmosphere is not devoid of
“weather.” Intense electric fields and a suite of upward
propagating, lightning-like discharges and blue-jet like
phenomena are a common, albeit transient, part of the
environment. Similarly, the role of thunderstorms in
generating hydrodynamical instabilities, shears and
significant vertical motions extending many kilometers
above visible storm tops is beginning to be appreciated.
Those planning to fly a variety of next-generation
vehicles in the lower layers of the “ignorosphere” should
not assume that this layer is quiescent. While perhaps
more properly referred to as “edge of space weather,” a
better understanding of these phenomena is required for
a wide range of disciplines besides aviation operations,
including studies of the global electrical circuit (Rycroft et
al. 2000), middle atmospheric NOx chemistry, aircraft
safety (Uman and Rakov 2003), infrasound research
(Bedard and Georges 2000) and RF propagation (Rodger
ACKNOWLEDGEMENTS. This material is based in part
was upon work supported by the National Science
Foundation, under Grant No. ATM-0221512 to FMA
Research, Inc. Special thanks to Victor Pasko, Eugene
Wescott, Patrice Huet, Mark Stanley, O.H. Vaughan,
Dave Sentman and Tudor Williams for supplying their
photographs. We wish to thank Dwight Bawcom, NASA
(retired) for providing information related to Flight 1482P.
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Figure 1. A montage of transient luminous events observed above thunderstorm systems from the ground, aircraft
and the Space Shuttle (top). Figure 2. Photograph of an “upward lightning bolt” which penetrated into the
stratosphere above an Australian thunderstorm system, while persisting for up to 2 seconds (bottom).
Figure 3. Evidence of the turbulent state of the atmosphere in the stratosphere above deep convective storms.
Figure 4. Numerical simulation of the vertical motions (lower panels) induced by an intense thunderstorm in
the clear air above storm tops (Droegemeier et al. 1997). Values of several meters per second occur. The top of
the modeling domain in this example was set at 20 km. We would expect that if the modeling domain were
extended upward to 30 km or higher, the impact of the storm would still be significant at those altitudes.