Cold wave

A cold wave is a rapid fall in temperature within a 24 hour period requiring substantially increased protection to agriculture, industry, commerce, and social activities. The precise criterion for a cold wave is determined by the rate at which the temperature falls, and the minimum to which it falls. This minimum temperature is dependent on the geographical region and time of year

A cold wave can cause death and injury to livestock and wildlife. Exposure to cold mandates greater caloric intake for all animals, including humans, and if a cold wave is accompanied by heavy and persistent snow, grazing animals may be unable to reach needed food and die of hypothermia or starvation. As a result of the after affects of these temperatures (i.e. cold, flu, pneumonia, etc.) all contributes to hypothermia.

Fires become even more of a hazard during extreme cold. Water mains may break and water supplies may become unreliable, making fire fighting more difficult. The air during a cold wave is typically denser and any cold air that a fire draws in is likely to cause a more intense fire because the colder, denser air contains more oxygen.

Cold waves that bring unexpected freezes and frosts during the growing season in mid-latitude zones can kill plants during the early and most vulnerable stages of growth, resulting in crop failure as plants are killed before they can be harvested economically. Such cold waves have caused famines. At times as deadly to plants as drought, cold waves can leave a land in danger of later brush and forest fires that consume dead biomass. One extreme was the so-called Year  without a Summer of 1816, one of several years during the 1810s in which numerous crops failed during freakish summer cold snaps after volcanic eruptions that reduced incoming sunlight.

Countermeasures

·                     Provision of shelters

·                     stock up on food, water, and other necessities before a cold wave.

·                     Choose to migrate to places of milder climates, at least during the winter.

·                     Smudge pots can bring smoke that prevents hard freezes on a farm or grove.

·                      Vulnerable crops may be sprayed with water that will paradoxically protect the plants by freezing and absorbing the cold from surrounding air.

Historical cold waves

Contemporary cold waves (2001-date)

·         Early 2012 European cold wave - 590 people died during a cold snap with temperatures falling below −35 °C (−31 °F) in some regions. Ukraine is the worst hit, with over 100 deaths related to the cold.

·         Winter of 2010–2011 in Great Britain and Ireland - It was referred to as The Big Freeze by national medias in both United Kingdom and Ireland and it was the coldest winter in Britain for 31 years with an average temperature of 1.51 °C (34.72 °F). The UK had its coldest December ever, since records began in 1910, with a mean temperature of −1 °C (30.2 °F). It easily broke the previous record of 0.1 °C (32.18 °F), set in December 1981.

·         2007 Northern Hemisphere cold wave - All of Canada and most of the United States underwent a freeze after a two-week warming that took place in late March & early April. Crops froze, wind picked up, and snow drizzled much of the United States. Some parts of Europe also experienced unusual cold winter-like temperatures, during that time.

20th-century cold waves

·         1995 White Earthquake in southern Chile - On August 1995 southern Chile was struck by a cold wave consisting in two successive cold fronts. Fodder scarcity caused a severe livestock starvation. Cows and sheep were also buried in snow. In parts of Tierra del Fuego up to 80% of the sheep livestock died.

·         1994 Northern US/Southern Canada cold outbreak - January 1994 was the coldest month recorded over many parts of the northeast and north-central United States, as well as Southern Canada, or coldest since the late 1970s in some locations. Many overnight record lows were set. Cold outbreaks continued into February but the severity eased somewhat. The cold also extended further south than usual into Texas bringing snowfall and temperatures lower than −20 °F (−28.9 °C) to parts of the state, Florida also experienced cold and snowfall, even once flurries were reported north of Miami and damage to the citrus crop in central Florida was extensive. Detroit, Michigan saw their coldest temperature since 1985.

Incidence of Heat Wave in South Asia (2007)

A heat wave is a hot period, which lasts from a few days to a few weeks, and which may be accompanied by high humidity. Severe heat waves could damage crop, and kill from hyperthermia.

If accompanied by drought, heat waves can lead to wildfires. As per the assessment made by IMD, the 2007 extreme heat waves in India were considered to be the fourth warmest year on record since 1901. In 2007, the annual average air temperature over India was 0.55 0 C above the averages between 1900 and 1961.1.  Further, as per the assessment, eight of the ten warmest years occurred in the decade 1997-2007. These warmest years were 2002, 2006, 2003, 2007, 1998, 2004, 1999, and 2001, in the order of warmness.

In India, the heat waves during April to June 2007 led increasingly higher temperatures. The heat waves were observed over coastal Andhra and Telangana during May.2.  The western Himalayan region was also warmer than normal during the last week of March and April and the first week of May 2007. As per EMDAT data, these events claimed more than 72 lives. The heat wave raised the maximum temperature above 5-7O C over the northern and central parts of India during the first 10 days of June 2007, which killed 72 people  during that period. The temperature anomalies of 2-10 June compared to the 1961 to 1990 average were higher over many parts of India

As per a Relief Web report, the 2007 heat wave in Pakistan claimed 232 lives.3,4 In June, more than 70 people died in the Central province of Punjab. Temperature to the extent of 50O

C was recorded over the North-West Frontier Province. The meteorological department registered a record maximum temperature of 52O C at Sibi.4