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Complex and intelligent life developed on Earth because it has retained sufficient water, primarily in liquid form, for several billion years. The loss of Earth’s water to outer space is limited by a cold trap at the top of its thick troposphere. Earth maintains a thick troposphere because the dipolar geomagnetic field deflects the solar wind, preventing ionized particles from heating the upper atmosphere and lowering the tropopause. Earth’s magnetic field is sustained by the dynamo action of convective motions within the outer core, which require a large flux of heat from core to mantle. Plate-tectonics, which provides the required rate of planetary cooling over billions of years, requires the presence of liquid water to make the plates ductile and to lubricate the plate boundaries. The sustained, coupled interaction of liquid water, atmospheric structure, the geomagnetic field and plate tectonics forms a feedback-loop which maintains Earth’s long-term habitability.

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The organizational activity carried out by W Foerster is described in connection with events following the Krakatoa eruption in 1883.

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Extracts from Otto Jesse's papers relating to twilight studies, noctilucent clouds and atmospheric movements are presented here to illustrate his contribution to the subject during the years 1884-1901. The most important result of his activity was the establishment of the Berlin “Atmospheric Programme” which included regular monitoring of noctilucent clouds by visual and photographic means. Furthermore, Jesse studied problems of dynamic processes in noctilucent clouds and in the corresponding upper atmospheric layers.

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Ground based observations of the “Széchenyi István” Geophysical Observatory of the Hungarian Academy of Sciences (Nagycenk) offer a unique opportunity for investigation of the complex processes of Earth’s environment and of its effect on radio wave propagation. High temporal resolution recording of variations of the geomagnetic field, vertical incidence sounding of the ionosphere and observation of whistlers enable determination of plasma density profiles in the inner magnetosphere (plasmasphere) and their changes. Study of ionospheric processes and their effects in the upper atmosphere (thermosphere) is supported by a permanent GPS station. Both DC and AC fields of lightning discharges are also recorded in the Observatory. Measurement of the DC field is related to the atmospheric electric circuit, where the global thunderstorm activity is the generator and fine weather areas play the role of loading. Loading of the atmospheric electric field depends on rate of ionization, ionization being caused by galactic cosmic rays. However, galactic cosmic rays are modulated by solar activity. Similarly amplitude of Schumann resonances depend on thunderstorm activity and its distance from the recording site. Resonance frequencies occurring at wave-lengths approximating dimensions of the Earth-ionosphere waveguide are affected by conductivity variations of the upper boundary of the cavity resonator and thus, by changes of thickness of the cavity resonator.

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