Caption: Lightning discharges appear in various colours depending on the scatter of light inside the thundercloud and in the atmosphere.The intracloud lightning discharges in the centre of the thundercloud appear to be white with a bluish tint, and the cloud-to-ground discharge below appears to be orange.The right hand side of the thundercloud exhibits a green tint that is attributed to the unique composition of hydrometeors inside the thundercloud.The photo was taken in the late evening of 10 September 2013, near Tarragona in northeastern Spain.

Near‐surface air temperature over the oceans is a relatively unused parameter in understanding the current state of climate, but is useful as an independent temperature metric over the oceans and serves as a geographical and physical complement to near‐surface air temperature over land. Although one complete version of this dataset exists (HadNMAT2), it has been strongly recommended that various groups generate climate records independently, which is one motivation here. This University of Alabama in Huntsville (UAH) study began with the construction of monthly night‐time marine air temperature (UAHNMATv1) values from the early‐twentieth century through to the present era using air temperatures on ships. Data from the International Comprehensive Ocean–Atmosphere Data Set (ICOADS) Release 3.0 (R3.0) were used to compile a complete time series of gridded UAHNMATv1. The observations required detailed homogenization procedures since there are many biases to account for such as increasing ship height and changing observing practices. The UAHNMATv1 dataset, once homogenized, is gridded to 5.0° monthly anomalies from 1900 to 2018. This study will present results which quantify the variability and trends and compare to current trends of other related datasets that include HadNMAT2 and sea‐surface temperatures (HadISST & ERSSTv4). This new dataset has broad overall agreement both globally and regionally with HadNMAT2, HadISST, and ERSSTv4 datasets.

The Intergovernmental Panel on Climate Change Assessment Report 5 (IPCC AR5, 2013) discussed bulk atmospheric temperatures as indicators of climate variability and change. We examine four satellite datasets producing bulk tropospheric temperatures, based on microwave sounding units (MSUs), all updated since IPCC AR5. All datasets produce high correlations of anomalies versus independent observations from radiosondes (balloons), but differ somewhat in the metric of most interest, the linear trend beginning in 1979. The trend is an indicator of the response of the climate system to rising greenhouse gas concentrations and other forcings, and so is critical to understanding the climate. The satellite results indicate a range of near-global (+0.07 to +0.13 degrees C decade(-1)) and tropical (+0.08 to +0.17 degrees C decade(-1)) trends (1979-2016), and suggestions are presented to account for these differences. We show evidence that MSUs on National Oceanic and Atmospheric Administration's satellites (NOAA-12 and -14, 1990-2001+) contain spurious warming, especially noticeable in three of the four satellite datasets.Comparisons with radiosonde datasets independently adjusted for inhomogeneities and Reanalyses suggest the actual tropical (20 degrees S-20 degrees N) trend is +0.10 +/- 0.03 degrees C decade(-1). This tropical result is over a factor of two less than the trend projected from the average of the IPCC climate model simulations for this same period (+0.27 degrees C decade(-1)).