Why does there seem to be more warmth around?
SUNDAY MAY 22, 2016
Earth is affected by our elliptical cycle around the sun, which creates seasons of the year. But the sun's heat varies each 11-12 and 22-23 years, which varies the temperatures of the seasons. Cycles of the moon also vary, which impacts the timing and intensity of weather events and patterns. So we must consider the orbits of sun and moon. Firstly, as we climbed to the solar peak in 2014, this encouraged solar warmth that melted parts of ice in Antarctica, in the polar summer sending greater amounts of cooler water northwards. Some of this extra volume of water flowed up the west side of S America, and because the currents cannot flow east due to the Americas, the currents' flow turned westwards, from Peru towards Australia, to become part of the La Nina system. This is entirely predictable and regular.
At the same time cold polar currents also flowed up the east side of Africa. When La Nina is in full swing it brings increased monsoon activity to India. Just like the sloshing in a bath, water levels increase near the middle of this two-pronged northward water flow from both east and west southern oceans, and gathers in the land-locked bays of the Arabian Sea and particularly the Bay of Bengal. This creates higher tides there, and therefore much flooding from heat-driven glacier thaw in the Himilayas, simply because the higher tides prevent water from tidally draining away. Just as a bath water slosh stops just before water flows back to the other end, so the currents then stall and it is called the neutral period between La Nina and El Nino.
Soon afterwards in this sequence, currents flow back eastwards towards Peru which get to be called El Nino. Currents control wind systems, and the NW monsoon that reaches WA and the top of Australia is the first stage of this flowback. Heavy rains also eventually reach southern Brazil. But when currents stall there is less mixing in the oceans, and therefore more heat on the sea surface, which by conduction warms the land. India then experiences warm seasons and weak monsoons. Weaker currents slow wind systems. El Nino puts the brake on cyclones because wind speeds are low.
The weak monsoon in 2013/14 at the top of Australia failed to deliver cooling rain to the Australian interior, which consequently overheated. Normally, cooler winds coming through the Australian Bight draw and dissipate (because heat flows to cold) this heat from this middle band of Australia down to the southern states. But weaker currents coming through the Bight slowed the wind systems that were passing through from Perth to Tasmania, enabling the southern portion of Australia to overheat also. The state of Victoria became tinder dry, and in turn at the same latitude, a short period of severe drought came to the North Island of New Zealand. To some extent we are currently recovering from that period, but it is being delayed because of lunar 'minor standstill'. What is this?
Because of the permanent 21-23° tilt of the earth, the moon crosses between both of earth's hemispheres every 27.3 days, called the Declination Cycle. This moves huge volumes of water across the equator, and changes barometric pressures. Over a cycle length of 18.6 years, the average latitude of the earth over which the moon reaches each month is around 23°N to 23°S. But every 9 years there is a minimum range called minor standstill, of the moon's trekking path reached, between 18°N over Earth to 18°S in the same 27.3 days, the last year of which was 2015.
In a further 9 years the moon will reach its maximum monthly range across the equator from one hemisphere to the other, reaching 28°N to 28°S in that same 27.5 day monthly time frame, the 'major' standstill, the last of which was in 2006, with the next due in 2025. The characteristic of minor standstill is a slower moon bringing weather patterns longer to both develop and last. Heat hangs around for longer. During major standstill years, weather systems are quicker to change.
A final factor is that full moons have combined with closer perigees from July to December of 2015. This combination brings warmer early summer to the southern hemisphere and a milder early winter to the northern hemisphere. These solar and lunar factors have enabled more warmth. We have been thus in the tail-end of influences from solar max, minor standstill, stalling of oceanic currents, lesser cyclones and drier Australian states.
By mid July, the next La Nina will be underway which will bring winter rain to lower Australia and much rain to most of New Zealand in October. Hawkes Bay can expect relieving rains from July onwards. Spring for NZ will become cooler. Also this July, heatwaves will affect both Europe and Texas, then Cyprus by mid August. Floods will again reach northern India in mid September. In July of 2017, heatwaves will repeat in the US and Europe, and in August 2017 the monsoon will return to Korea, Phillippines, Thailand and Vietnam.
Postscript: NZ and Australia are receiving cold winter blasts at time of current writing, because of the moon's southern declination. Every winter, it is the timing of the southern declination that always brings the snow. But this winter, in both islands, the snows will melt again fairly quickly from warm winter rains. It may not be until late winter that enough snow and/or colder temperatures will have accumulated to enable the opening of most ski fields.
© Ken Ring 2016