We’re Having a Heat Wave

For nearly a week the mid-east of the United States and Canada has been experiencing record breaking heat. Newark, Washington DC. Baltimore, Portland, Concord, Providence have all had record temperatures at or very close to 42C. In fact some 220 individual heat records for July have been broken. New York City has so far not broken its record, but the thermometer hovers just one degree away from it. In most places the humidity has been high, so it feels even hotter than the temperature records.

Half the US population has been given a “heat advisory”, which is a severe heat warning, and some people have died as a result of the extreme heat.

Heat waves bring with them a number of problems beyond the problem of people trying to keep cool. Electricity voltage is usually reduced to avoid the risk of cables overheating. In the transmission of electricity heat is usually given off through cables, because electrical power loses power through heat in the delivery of the electricity from where it is created to where it is used. In very hot weather the power cables, heated up by the transmission, cannot lose heat, because the surrounding areas through which they lose heat when they run underground are hotter than the cables, and heat can only move from a hot place to a cooler place. The only solution in the case of underground cables is to reduce the voltage – the amount of power flowing through the cable.

Voltage reduction has been used for some years by electricity companies as a way of rationing current. When voltages are reduced you may experience fridges and air conditioning units being turned off because enough power is not flowing through, and you will definitely experience less light from low voltage lighting. However, the losses have to be made good and are often exceeded by people having to power up equipment such as electric water heaters when the voltage is restored. In the case of the present North American heat wave voltage reduction is not being used for rationing or to save energy, but simply to prevent the underground powewr cables from overheating and becoming dangerous.

Another effect of a heat wave on infrastructure is that roads melt. Often they are built to a specific standard and to save money roads are built to finer engineering tolerances than the engineers would design so in exceptionally hot weather and exceptionally cold weather roads very frequently deteriorate very quickly.

Infrastructure design is just one of the things that have to be re-thought with the very slow and gradual onset of climate change. We have got used to building infrastructure to withstand known conditions, and we must now build it to withstand as yet unknown but likely future extreme conditions.

2 Responses

  1. Im envious,

    My city has just had 12 inches of snow and some sub zero nights.

    This almost never happens, maybe snows about once every 10 years and then never this much.

    The cold air swept the length of the country and then presumably went NE to cool the rest of the pacific region.

    Pesky climate change wot?

    Cheers

    Roger

    http://www.rogerfromnewzealand.wordpress.com

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