Showing posts from April, 2016

More and more extreme weather

The weather is getting more and more extreme. On April 23, 2016, temperatures in India were as high as 47.7°C or 117.9°F. At the same time, temperatures in California were as low as -12.6°C or 9.2°F, while temperatures in Greenland were as high as 3.6°C or 38.6°F. Meanwhile, Antarctica was as cold as -60°C or -76°F. The situation in India is most worrying. Temperatures are very high in many locations. India has been experiencing heatwave conditions for some time now, as reported in  this  and in  this  earlier posts. [ click on images to enlarge ] More extreme weather goes hand in hand with changes that are taking place to the jet stream, as also discussed in earlier posts (see further below). As the Arctic warms up more rapidly than the rest of the world, the temperature difference between the Equator and the North Pole decreases, which in turn weakens the speed at which the north polar jet stream circumnavigates the globe. This is illustrated by the wavy patterns of the north polar j

Can we Design Hydrogen-Fuelled Aircraft?

Can we Design Hydrogen-Fuelled Aircraft? S H Salter, Engineering and Electronics, University of Edinburgh.EH9 3JL. The collection of temperature measurements by David Travis following the 3-day grounding of all US civilian flights after 9/11 showed the astonishing effect of jet exhaust on the environment. If burning hydrocarbon fuel in the stratosphere ever becomes a criminal offence, the aviation industry will have an interesting problem. A possible solution is the use of hydrogen as a fuel. Is this technically possible? The Airbus 380 carries 250 tonnes of fuel with a total calorific value of about 1013 joules. Fuel is stowed in wing tanks but this would be a volume of about one eighth of the fuselage. The calorific value per unit mass of hydrogen is about 3.5 times that of jet fuel and so the weight of hydrogen for the same range would be only about 70 tonnes. Unfortunately the ratio of density of jet fuel to un-pressurized hydrogen is about 9000, so the design problem is how

March temperature

Above image shows Land-Ocean (in red) and Land-only (in black) global monthly temperature anomalies compared to the average over the period 1951-1980. At the Paris Agreement, nations committed to strengthen the global response to the threat of climate change by holding the increase in the global average temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels. To see how much temperatures have risen compared to pre-industrial levels, a comparison with the period 1951-1980 does not give the full picture. The image below, created by selecting a smoothing radius of 1200 km, shows that the global temperature rise from 1890-1910 was 1.58°C or 2.84°F. The temperature rise is even higher when looking at measurements from land-only stations. The image below compares the March 2016 temperature with the period from 1890-1910 (250 km smoothing), showing a Land-only anomaly of 2.42°C or 4.36°F. Taking int

Record Arctic Warming

On April 3rd, 2016, Arctic sea ice extent was at a record low for the time of the year, reports the National Snow and Ice Data Center ( NSIDC ). The image below, created with an image from the JAXA site , gives an update on sea ice extent. Besides sea ice extent, sea ice area is important. For more on what constitutes "ice-covered" and what is sea ice extent (versus sea ice area), see this NSIDC FAQ page . Another measure is sea ice area. On April 2nd, 2016, Northern Hemisphere sea ice area was at a record low for the time of the year, reports the Cryosphere Today . In 2015, there still was more sea ice area than there is now when it was half a month later (15 days) into the year. In 2012, there still was more sea ice when it was 25 days later in the year. In other words, sea ice area decline is almost one month ahead compared with the situation in 2012. NSIDC scientist Andrew Slater has created the chart below of freezing degree days in 2016 compared to other years at Latitu