Weather & Climate
The earth's tilt, rotation and land/sea distribution affect the global
weather patterns we observe. While the weather varies from day-to-day at any
particular location, over the years, the same type of weather will reoccur. The
reoccurring "average weather" found in any particular place is called climate.
Weather measurements (maximum temperature, minimum temperature, wind speed and
direction, rainfall, etc.) for any place, for any day, over a fixed number of
years, determines the average weather. Averaged weather values represent
the climatic normal weather for that day. From the National Centers for
Environmental Information: "the climatic normal is simply the
arithmetic average of the values over a 30-year period. The current set of
climate normals is based upon observed weather in the years of 1981 to 2010. In
2021, a new set of climate normals will be generated based upon the observed
weather between 1991 and 2020.”
Climate change is the most threatening
effect of recent human activities. For example, climate scientists have
hypothesized that Arctic sea ice decline, reduced snow cover, changing
evaporation patterns, and other weather anomalies are expected to make the
Arctic heat up faster than other parts of the globe.
Weather in its simplest form is the expression of heating and cooling effects. When wind blows the roof
off a house, the energy required was supplied by the sun. The energy may have
been stored briefly in the water of a lake or ocean and then expressed through
evaporation of the water and heating of the air. Air moves when there is a
pressure gradient that is another result of heating and cooling. The water vapor
content of the atmosphere will increase in a greenhouse-warmed world. With more
water vapor in the atmosphere and an increase in sea surface temperatures, there
will be increased precipitation at times and more vigorous storms and floods.
The attempt to understand complex systems has taken a quantum leap in recent
years. We have gone beyond naïve linear models and now appreciate that if
complex systems such as the atmosphere, the oceans, and land ecosystems change,
they may become unstable and more unfriendly.
Heat drives weather and
increased heat means warmer ocean water and turbulence in the atmosphere. The
consequences of increased greenhouse gases have to do with the distribution of
this extra heat and its effect on ocean and air circulation patterns. We can
accept paradoxical weather results as the extra heat is unevenly distributed and
makes weather more unstable.
The warmest years on record since
instrumental climate records began in 1850 were 1998, 2005, 2010 and 2016.
Warming continues in 2017 with heat waves, droughts, hurricanes and forest fires. The
average global sea-surface and land-surface air temperature from December 2007
to November 2008 was 14.3 °C according to the World Meteorological Organization. The 2013 global average ocean
temperature was 0.48°C (0.86°F) above the 20th century average of 16.1°C (60.9°F)
and tied with 2006 as the eighth highest annual temperature on record and the
highest since 2010. In 2016, the world's surface was warmer than average and, in
some locations, record warm during August 2015, contributing to the monthly
global record warmth. The combined average temperature over global land and
ocean surfaces for August 2015 was 0.88°C (1.58°F) above the 20th century
average of 15.6°C (60.1°F) and the highest August in the 136-year record. The
WMO temperature analysis is based on land-based weather stations in 188
countries, complemented by measurements from ships, buoys and satellites. NASA’s
Goddard Institute for Space Studies and the UK Met Office both contributed their
own data to the WMO analysis and independently arrived at similar determinations
of surface temperature.