In my climate science refresher series, I reproduced a temperature and SOI graph in an attempt to show that El Nino does not cause global warming. When I made the graph, I used a 20-year filter of the data instead of a shorter time period, which smoothed out the effects of shorter time period events. Since El Nino has a period of about 7-10 years, and the climatic effects of volcanoes last about 2 years, both of these were essentially eliminated from my plots. I have replotted the now monthly-averaged data instead of the previous yearly-averaged data seen below.

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This looks like an interesting paper: The surface energy balance and the mixing height in urban areas—activities and recommendations of COST-Action 715. Abstract and first figure included below.

Abstract: The specific problems of determining and simulating the surface energy balance (SEB) and the mixing height (MH) over urban areas are examined. The SEB and MH are critical components of algorithms and numerical models for the urban boundary layer, though the constituent parts of the SEB and the MH are not routinely measured by national weather services. Parameterisations are thus needed in applications. In this investigation, several recently developed algorithms and models for estimating the SEB and MH were applied to new datasets and assessed. Results are discussed in terms of the need for spatial resolution and the parameters needed to describe the urban atmosphere. Limitations of models are identified and recommendations for further development and observations are given. Having identified gaps in knowledge, key findings from new urban experiments and numerical modelling for the SEB and MH are given. The diurnal cycle for the SEB is significantly different from rural conditions—urban heat storage is needed in urban parameterisations. The urban MH is increased over the rural MH, as shown by several numerical schemes and careful sodar analyses. This work has been carried out within the COST-715 Action “Meteorology applied to urban air pollution problems (1998–2004). COST 715 reached a consensus proposing representatively sited measurements of meteorological parameters and turbulent fluxes above roof-tops, and recognised that such data are needed to improve numerical models of the urban surface processes.

Hansen, J., Mki. Sato, P. Kharecha, G. Russell, D.W. Lea, and M. Siddall, 2007: Climate change and trace gases. Phil. Trans. Royal. Soc. A, 365, 1925-1954, doi:10.1098/rsta.2007.2052. [PDF]

Paleoclimate data show that the Earth’s climate is remarkably sensitive to global forcings. Positive feedbacks predominate. This allows the entire planet to be whipsawed between climate states. One feedback, the “albedo flip” property of water substance, provides a powerful trigger mechanism. A climate forcing that “flips” the albedo of a sufficient portion of an ice sheet can spark a cataclysm. Ice sheet and ocean inertia provides only moderate delay to ice sheet disintegration and a burst of added global warming. Recent greenhouse gas (GHG) emissions place the Earth perilously close to dramatic climate change that could run out of our control, with great dangers for humans and other creatures. Carbon dioxide (CO2) is the largest human-made climate forcing, but other trace constituents are important. Only intense simultaneous efforts to slow CO2 emissions and reduce non-CO2 forcings can keep climate within or near the range of the past million years. The most important of the non-CO2 forcings is methane (CH4), as it causes the 2nd largest human-made GHG climate forcing and is the principal cause of increased tropospheric ozone (O3), which is the 3rd largest GHG forcing. Nitrous oxide (N2O) should also be a focus of climate mitigation efforts. Black carbon (”black soot”) has a high global warming potential (~2000, 500, and 200 for 20, 100 and 500 years, respectively) and deserves greater attention. Some forcings are especially effective at high latitudes, so concerted efforts to reduce their emissions could still “save the Arctic”, while also having major benefits for human health, agricultural productivity, and the global environment.

Several figures, captions, and text have been reproduced in this post under fair use. No copyright claims are made and readers are encouraged to read the entire paper, freely available at the link at the top of this post.
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Lightnings are phenomena of electrical discharge that happen whenever a great potential difference occurs between clouds, parts of a cloud, or between a cloud and the earth. If the discharge occurs between a cloud and the earth’s surface, the cloud possesses a negative charge, the soil underneath positive.

What mechanism gives rise to such big potential difference, and what other phenomenon is produced by it besides lightnings?

During storms, strong currents of warm and humid air ascend with velocities that can reach one hundred kilometers per hour (a few months ago in Australia a paraglider was unwillingly pulled about 10,000 meters above sea level by such a current)…

More at The Origins of Lightnings.