This paper studies the response of the middle atmosphere to the 11-year solar cycle. The study is based on numerical simulations with the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA), a chemistry climate model that resolves the atmosphere from the Earth’s surface up to about 250 km. Results presented here are obtained in two multi-year time-slice runs for solar maximum and min...

The spectral distribution of the solar radiation reaching the Earth's surface depends on the irradiance emitted by the Sun, the Earth-Sun distance, and the transmission properties of the atmosphere. The changing Earth-Sun distance due to an eccentric orbit implies that the irradiance received at the top of the atmosphere varies with an annual cycle, being 6.9% above and below the yearly mean. T...

This tutorial focuses on basic physical concepts relevant to the heating of the corona and acceleration of the solar wind. We begin with a discussion of observations of the solar wind and solar corona and then develop a simple theoretical framework that allows us to explore some implications of the observations. Next we turn to observations of the lower solar atmosphere and their implications f...

The water abundance in a planetary atmosphere provides a key constraint on the planet’s primordial origins because water ice is expected to play an important role in the core accretion model of planet formation. However, the water content of the solar system giant planets is not well known because water is sequestered in clouds deep in their atmospheres. By contrast, short-period exoplanets hav...

Magnetic reconnection plays a crucial role in violent energy conversion occurring in the environments of high electrical conductivity, such as the solar atmosphere, magnetosphere, and fusion devices. We focus on the morphological features of the process in two different environments, the solar atmosphere and the geomagnetic tail. In addition to indirect evidence that indicates reconnection in p...

We have the strongest of reasons to infer the existence of free electricity in the sun. At high temperatures in the laboratory carbon and other elements emit great numbers of negatively charged partices, while friction, collision and exposure to ultra-violet light may be mentioned among various other agencies capable of producing free electrons under solar conditions. On the other hand, the pre...

This paper concentrates on rendering the solar disc considering Rayleigh scattering, Mie scattering, absorption, and refraction. The atmosphere is modeled in layers, each layer having a set of individual optical properties. Based on different atmospheric temperature profiles and climates, the solar disc is rendered in realistic shape and color. In particular, we replicate optical phenomena such...

The convergence of heat below subsidence inversions was estimated from radiosonde ascents on fine summer days. Sensible heat input from the ground was estimated from measurements of heat fluxes and net radiation over a wheat field. Absorption and back scattering of solar radiation by aerosol throughout the atmosphere were calculated from measurements of solar radiation at the ground. Radiation ...

Abstract. An admittedly pedantic but hopefully useful and informative analysis is presented of the EUVE 70–180 Å spectra of nine polars. These spectra are fit with three different models—a blackbody, a pure-H stellar atmosphere, and a solar abundance stellar atmosphere—to reveal the presence of spectral features such as absorption lines and edges, and to investigate the sensitivity of the deriv...

Within the next few years, GAIA and several instruments aiming to image extrasolar planets will be ready. In parallel, low-mass planets are being sought around red dwarfs, which offer more favourable conditions, for both radial velocity detection and transit studies, than solar-type stars. In this paper, the authors of a model atmosphere code that has allowed the detection of water vapour in th...