The influence of ground slab permeability on wall moisture in a historic buildingThe influence of ground slab permeability on wall moisture in a historic buildingThe influence of ground slab permeability on wall moisture in a historic buildingThe influence of ground slab permeability on wall moisture in a historic building

When impermeable ground bearing slabs are installed in old buildings without a damp-proof course, it is a common belief of practitioners within the conservation industry that ground moisture will be ‘driven’ up adjacent walls by capillary action. However, there is limited evidence to test this hypothesis. The accumulation of moisture in walls can promote the decay of the wall materials, decrease the thermal performance of the building envelope and adversely affect the comfort and health of occupants. An experiment was used to determine if the installation of a vapour-proof barrier above a stone flag floor in a historic building would increase moisture content levels in an adjacent stone rubble wall. This was achieved by undertaking measurements of wall, soil and atmospheric moisture content over a three-year period. Measurements taken using timber dowels showed that the moisture content within the wall did not vary in response to wall evaporation rates and did not increase following the installation of a vapour-proof barrier above the floor. This indicates that the moisture levels in the rubble wall were not driven by capillary rise.

Atmospheric dynamics on terrestrial planets with eccentric orbits

<p>The insolation a planet receives from its parent star is the main engine of the climate and depends on the planet's orbital configuration. Planets with non-zero obliquity and eccentricity experience seasonal insolation variations. As a result, the climate exhibits a seasonal cycle, with its strength depending on the orbital configuration and atmospheric characteristics. In this study, using an idealized general circulation model, we examine the climate response to changes in eccentricity for both zero and non-zero obliquity planets. In the zero obliquity case, a comparison between the seasonal response to changes in eccentricity and perpetual changes in the solar constant shows that the seasonal response strongly depends on the orbital period and radiative timescale. More specifically, using a simple energy balance model, we show the importance of the latitudinal structure of the radiative timescale in the climate response. We also show that the response strongly depends on the atmospheric moisture content. The combination of an eccentric orbit with non-zero obliquity is complex, as the insolation also depends on the perihelion position. Although the detailed response of the climate to variations in eccentricity, obliquity, and perihelion is involved, the circulation is constrained mainly by the thermal Rossby number and the maximum temperature latitude. Finally, we discuss the importance of different planetary parameters that affect the climate response to orbital configuration variations.</p>

Investigating the Dynamics of Hothouse Earth Climates with a Simplified GCM

<p>There are records of past Earth climates that were ice-free all the way to the poles (Barron 1983), which can be described as “hothouse” climates. These hothouse climates can be contrasted with an “all-tropics” planet, where the tropics are defined by the atmospheric dynamics, i.e. the Hadley Cell extent (Faulk et al. 2017). This classification is thus primarily dependent on a planet’s rotation, rather than its ice-free extent or surface temperatures. We investigate the parameter space between Earth and an all-tropics world using the open-source GCM Isca, developed by Vallis et al (2018). We take an Earth analog and perform a parameter sweep in three dimensions: global reservoir depth (1000m, 100m, 10m, 1m, 1cm); global saturation vapor pressure (1.5x current, 1.4x, 1.3x, 1.2x, 1.1x, 1x); and rotation rate (16 days, 8 days, 1 day). The sweep will allow us to explore the effects of surface liquid coverage, atmospheric moisture content, and large-scale atmospheric circulation on an Earth-like climate. In this presentation we provide a status report and analysis of initial findings.</p>