Challenge to established views

     

 22   The difficulty with the cloud-to-ground flash mechanism for delivering negative charge to the ground is that the diurnal modulation amplitude of averaged electric field data is modest (about 40% of the mean). The diurnal variation of total area covered by thunderstorms (bottom panel of figure 7) shows a modulation amplitude that is at least twice as large as the modulation of the Carnegie curve. The classic pic­ture solved this problem by assuming a uniform population of oceanic thunderstorms that satellite data have shown do not exist.

23   In a controversial 1993 paper Earle Williams and Stan Heckman of MIT constructed a model by adding the global sum of point discharge currents from St. Elmo's fire and corona produced by electrified rain clouds to the current from lightning activity and produced a curve with a modulation amplitude that is in better agreement with the Carnegie curve. They concluded that a significant fraction of the current flowing in the global circuit is more likely carried by point discharge currents than by lightning flashes. A related study can be interpreted to mean that if all lightning activity were to stop, other processes would maintain V₁ at 60% of the present average.

24 Another controversial new idea is that the global electric circuit integrates global thunderstorm activity into proxy variables for the mean global surface temperature and that these proxy variables are much more sensitive to global warming than a measure of the mean global temperature itself.

25 Although this idea remains unproven, the logic behind it is intriguing. The vigor of the vertical convection of the air increases when the temperature gradient (lapse rate) steepens. All global atmospheric circulation model results for an Earth with increased greenhouse gases yield increases in the planetary surface temperature and decreases the tropopause temperature; this combination should increase the lapse rate and therefore be destabi­lizing. Furthermore, increasing the surface temperature should exponentially increase the water vapor flux into the atmosphere, as described by the Clausius-Clapeyron equation. During global warming, increases in energy at the surface go into both the sensible heat of the air and the latent heat of the water vapor. The latter energy is released in cloud convective activity.

26 The power in the 8 Hz Schumann resonance emission line, and the total current in the global circuit, have been, found to correlate with global temperature changes on time scales ranging from the diurnal, through the sea­sonal, to the El Nino Southern oscillation scale. The UT dependence of the electric field demonstrates the response of the circuit to changes in Earth's surface temperature. The modulation amplitude of the electrical response is about 40% of the mean, whereas the diurnal temperature change over the land is less than 10%. Both parameters must be monitored, because Schumann resonance intensity depends upon the height of the ionosphere, which is known to have a solar cycle dependence and to respond to solar flares, geomag­netic storms and solar proton events. If 60% of the average V₁ arises from electrified rain cloud currents, the possibility exists that a combination of

 

Schumann resonance power level and V₁ monitoring could be used to infer proxy measures of both global temperature and global rainfall rates.

27   A third controversial question about the global circuit concerns the existence of coupling mechanisms that give the circuit a larger role than that of a passive load on the troposphere. In a provocative series of papers, Brian Tinsley and his coworkers at the University of Texas at Dallas have reemphasized the role of the global circuit in Sun—weather coupling and suggested mechanisms whereby the low modulation power provided to the global circuit by the solar wind is amplified enough to affect the weather. For example, to intensify a winter storm in the Gulf of Alaska with a global circuit fluctuation, a suc­cessful model must provide for a power amplification factor of about 10⁷. Tinsley assigns a critical role to an increase in the rate of ice crystal formation caused by the accumu­lation of electrostatic charge on droplets and ice crystals, with the accumulation being attributed to poorly under­stood processes known as ionization nucleation and electrofreezing. This step occurs prior to the generation of strong electric fields within clouds by microphysical ice processes. According to Tinsley, the air-Earth current, which transports charge to the cloud and polarizes the particles in the cloud, can act to increase the net charge on cloud particles and thus play an active role in this coupling process.

As we have seen, one result of the renaissance in the study of the global electric circuit consists of findings that are inconsistent with the standard paradigm. We believe that these anomalies make it clear that more measure­ments are needed to refine models of the global circuit.

 

 

 

 

Figure 7. Diurnal variation of electric-field strength and storm area. The top curve is the average potential gradient (the negative of the quantity in the previous figure) measured by the research vessel Carnegie during fair weather, plotted as a function of Universal time. The bottom curve is the inferred continental thunder area, also shown as a function of UT. The quantity plotted is the area that would be covered by thunderstorms if thunderstorms occurred only over land and if the probability of thunderstorm occurrence were globally identical to the probability observed as a function of UT at Kew Observatory.

 

We have based this article in part on a recent review in the technical literature that one of us (Bering) undertook. Our research was supported by the National Science Foundation and the Conly Research Foundation. We thank Michael Baginski, Richard Blakeslee, Les Hale, Bob Holzworth, Hua Ни, Umran Inan, Mi­chael Kelley, E. Philip Krider, Ralph Markson, George Reid, Lothar Ruhnke, Dave Sentman, Brian Tinsley, the late Bernard Vonnegut and Earle Williams for useful discussions and for providing re­prints. However, all views expressed in this article are our own. We apologize to anyone whose work has been inadvertently omitted

 

 

V. Reading for General Understanding

A Check the comprehension of the texts “The Conducting Atmosphere”, “Generators and Sources”, “Monitoring the Global Electric Circuit”, “Challenge to Established views” by choosing the answer, which you think, is correct.

1. What kind of electric field exists at Earth’s surface or a clear day?

a. upward

b. down ward

c. left ward

2. What are the “wires” in the global circuit made of?

a. thick wire

b. thin belts

c. thin air

3. When does the lightning flash complete the global circuit?

a. when it occurs from the ground to the cloud

b. when it occurs from the bottom of the cloud to the ground

c. when it occurs from very tall clouds to the bottom of the cloud

4. Who began continuous measurements of the atmospheric electric field and when?

a. by Maxwell                                     a. in 1850

b. by Kelvin                                        b. in1950

c. by Hall                                            c. in 1861

5. What does the UT dependence of the electric field demonstrate?

a. the response of the circuit to changes in Earth’s surface temperature

b. the increase in air temperature

c. the lowering of the total current in the global circuit

 

B Pick out from the texts “The Conducting Atmosphere”, “Generators& Sources”, “Monitoring the Global Circuit” and “Challenge to Established Views” all the word combinations with the following words (terms) and give their Russian equivalents.

rays                                     ionosphere

reaction                               charge

properties                             current

surface                                 field

response                              particles

conductivity                        mechanism

 

VI. Reading for Detail and Language Study.

 

1. Find in the texts “The Conducting Atmosphere” “Generators and Sources”, “Monitoring the Global Circuit” and “Challenge to Established Views”. the English equivalents for the following phrases.

- положительная пластина конденсатора

- силовые линии магнитного поля

- температура на поверхности земли

- солнечные вспышки

- всемирное потепление

- зависимость от солнечного цикла

- профиль проводимости

- профиль высоты электрического поля обратно пропорционален профилю проводимости

- без излучения, уравнения Максвелла могут быть приведены к единственному уравнению

- когда происходит вспышка молнии

- маленькие частички льда на верху облаков …

- самый часто встречающийся вид молнии …

- постоянное измерение атмосферного электрического поля

- механизм для доставки отрицательного заряда в землю

- нормы осадков по всему земному шару

 

2. Explain the meanings of the following words and expressions

- a downward electric field

- global electric circuit

- turbulent vertical flow

- ice crystal formation

- tall cumulus clouds

- cloud-to-ground lightning strokes

- average value

- high latitudes

- point discharge currents

- water vapour flux

 

3. Translate any of the three parts of the above texts in written form.

 

4. Translate the following phrases into Russian.

 

1. Thunderstorms are thought to be the most powerful of the sources by a factor of three.

2. Many attempts have been made over the years to confirm the Wilson hypothesis.

3. …the “charge on the outer plate” of the capacitor is distributed throughout the atmosphere rather than being concentrated at a single level.

4. Turbulence in this layer causes the physical properties of the boundary layer air to be modified because of its contact with the surface.

5. The values of the conduction currents observed above individual thunderstorms were found in one study to vary between 0.09 and 3.4A, with an average value of 1.7A.

6. A related study can be interpreted to mean that if all lightning activity were to stop, other processes would maintain VI at 60% of the present average.

7. All global atmospheric circulation model results for an Earth with increased greenhouse gases yield increases in the planetary surface temperature and decreases in the tropopause temperature …

 

5. Read the proper names.

 

Wilson [´wilsən]

Schumann [∫umən]

Kelvin  [kelvin]

Carnegie [ka:nədzi]

Clausius-Clapeyron equation [klosiəs-kleipirən]

Stan Heckman [´stæn ´hekmən]

Brian Tinsley [´braiən ´tinsli]

El Niño [əl´ninjə]

Earle Williams [´ə:l wiljəmz]

 

 

VII Oral Practice

A Answer the following questions:

1. What kind of electric field exists at Earth’s surface on a clear day?

2. Do people notice the electric field being on the Earth’s surface?

3. What keeps people from noticing the electric field?

4. In what way does William Thomson explain the fair-weather electric field?

5. What are the sources of driving the global circuit?

6. What returns the charge to the thunderstorms and closes the global circuit?

 

 

The Conducting Atmosphere

1. What influences the electrical properties at the atmosphere? Why?

2. How large is the lifetime of ions in the lower atmosphere?

3. When do the large ions form?

4. What is the conductivity at 100 km altitude?

5. Where does the columnar resistance occur?

6. In what way can one calculate the capacitance of the spherical capacitor?

7. What is important outside of the clouds and above the boundary layer.

 

Monitoring the global electric circuit

 

1. Is it easy to measure the fair-weather electric field?

2. Who began continuous measurements of the atmospheric electric field? When?

3. Why is the thunderstorm rate not a constant?

4. What masks the electric fields of global origin?

5. What is the Carnegie curve?

6. What is the best place on Earth for making ground-level observations of the global circuit?

 

B   Make comments on the text “Challenge to Established Views”

C Render the text “ Generators and Sources”.