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Climate

Climate and weather patterns on the Kenya Coast

2014 September Equinox

on Monday, 22 September 2014. Posted in Climate

23rd September 2014

2014 September Equinox

The 2014 September (southward) Equinox (Tuesday, 23rd September) - marks equal day and night over the equator. The closest point of the earth to the sun (the 'subsolar point') moves over the equator towards the southern hemisphere.

A transitional period of shifts in the mosnoon winds called 'Matalai' occurs from mid-September to mid-November where there is a period of rains and little wind between the switch from the southerly Kusi to the north easterly Kaskazi.

'Winter Solstice' - 21st December

on Thursday, 13 December 2012. Posted in Climate

Doomsday predictions, the Mayan Calendar, and another significant celestial date.

'Winter Solstice' - 21st December

The 21st of December 2012 is the 'Winter' Solstice, when the Earth's position is tilted to it's extreme and the Tropic of Capricorn is the closest latitide to the sun. 

This is the southern hemisphere's longest, day, and the northern hemisphere's shortest day.

Theories of the end of the world stemming from the Mayan Calendar are widespread. The reality is that the calendar does indeed end a long count period on this day, but not the end of the calendar completely, just as modern day calendars end on the 31st of December.

March Equinox

on Sunday, 20 March 2011. Posted in Climate

20 March 2011 - Equal day and night over the equator

March Equinox

Sunday March 20th 2011 marks the March Equinox when the subsolar point begins to move into the northern hemisphere bringing longer days to northern latitudes for the next 3 months.

On the Kenyan Coast in equatorial latitudes - the equinox also announces the arrival of the Intertropical Convergence Zone (ITCZ), which brings with it some heavy rainfall. The ITCZ generally follows a few weeks later - which is why the first rainy season of the year occurs in April and May.

Kenya Coast Weather

on Monday, 14 March 2011. Posted in Climate

Rainfall and Temperature patterns on the Kenya Coast

Kenya Coast Weather

The major influence on East African weather is the Inter-tropical Convergence Zone (ITCZ). This is an area of the atmosphere above the earth’s surface where two air-streams (the North East and South East Trade Winds) converge.

The zone is characterised by warm rising air and the formation of clouds, and is clearly visible as an equatorial band oscillating north and south across the equator as the earth revolves around the sun on it’s annual orbit along the plane of the ecliptic.

The ITCZ and Rainfall Patterns on the Kenya Coast

on Friday, 29 October 2010. Posted in Climate

Article 3/3: An overview of the Kenya Coast's climatic model

The ITCZ and Rainfall Patterns on the Kenya Coast

As described in the previous article - the earth orbits the sun with it's axis tilted at an angle of about 23.4 degrees in relation to the Plane of the Ecliptic. The resulting effect of the sun's changing position in the sky causing the subsolar point to move between the tropics, and across the equator twice a year causing a change in the season's in the northern and southern hemisphere, and more locally in East Africa, the changing of the monsoon winds, and the alternating wet and dry seasons.

 

This article looks at the Kenya Coast's weather pattern in more detail and outlines a generalised climate model for this region.

 

The equatorial region's weather patterns are dominated by the Hadley Cell, an atmospheric circulation pattern occurring between the tropics that produce the easterly trade winds.

 

In the Hadley cell, air rises near the equator, flows out towards the poles at high altitude, descends back to the Earth's surface at the outer edges of the tropics, and completes the cycle by flowing back towards the equator near the earth's surface.

Why the Monsoon Winds Change

on Tuesday, 26 October 2010. Posted in Climate

Article 2/3: Why the East African Monsoon Winds change at the same time each year

Why the Monsoon Winds Change

The regularity and predictability of the East African monsoon winds have been the driving force behind the shaping of the East African Coast's human geography for centuries. So what explains why this regular wind pattern repeats itself in such a similar fashion around the same times of year, every year.

As described in the previous article - the period of change for the east african monsoon winds is in March and September, by no coincidence - these times of year are also the timings of the equinox - equal day and equal night over the equator.

As the earth orbits the sun along the Plane of the Ecliptic (it's orbital path) it is not angled vertically, but rather tilted at an angle of approximately 23.4 degrees, such as a spinning top angled over slightly to one side. The earth constantly remains at this angle throughout it's annual orbit. It is this tilted axis that causes the sun's position to change in the sky and hence lead to seasonal changes throughout the year.

The East African Monsoon Winds

on Tuesday, 19 October 2010. Posted in Climate

Article 1/3: A brief overview of the winds influencing the Kenya Coast

The East African Monsoon Winds

The equatorial Kenya Coast has a rich and ancient history, thanks in no small part to the magnificent Indian Ocean, with its consistent and relatively predictable monsoon 'tradewinds' that have been an integral part of coastal life for the peoples of this region for many centuries. The pattern of these winds has been understood and harnessed by mariners, traders and explorers from as far off as Arabia, India and China. The word monsoon is said to originate from the Arabic name for these winds - 'muusum'.

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