Ascension : Weather Report
Submitted by The Islander (Met Office) 16.07.2009 (Article Archived on 30.07.2009)

Statistics for the week ending Monday 13th July 2008

Statistics for the week ending Monday 13^th July 2008

	Max (Celsius)	Min (Celsius)	Rainfall (mm)
AIRHEAD	28.8	23.3	Trace
TRAVELLERS	28.4	20.8	0.6
RESIDENCY	-	-	-
GEORGETOWN	31.2	22.2	Trace
ST. HELENA	20.8	14.1	12.6
FALKLANDS	6.3	-3.6	11.0
UK (Brize Norton)	22.2	8.0	51.8

ASCENSION:  A mostly fine, dry, quite sunny week. Just a few light rain showers from time to time.

ST HELENA: Mainly fine, dry weather until Thursday, then increasingly showery through Friday and over the weekend. The light to moderate East to Se’ly breeze becoming rather fresh and gusty during Saturday.

UK: An area of low pressure moved northeast over Britain early in the week to bring a cooler flow from the north. This also brought some heavy thundery showers. Fine later in the week, before another Atlantic low brought some rain over the weekend.

FALKLANDS: Typical cool winter weather, with some overnight mist and fog and patchy rain or drizzle at times. Things taking a turn for the worse as we moved into Monday 13th with strong SW winds and frequent snow showers with sub zero temperatures. 9cm snow depth by Monday morning, and more to come. Hence Monday’s flight delayed on the southbound leg.

***************

Early last week we had some very clear and cloudless conditions, and one day after dinner, as the sun set below the horizon, talk turned to the possibility of a “Green Flash”.

A "green flash" or "emerald flash" is a rare optical phenomenon that occurs during or shortly after the set and during or before the rise of the sun, when a green spot, or “flash”, is visible for a short period of time.  It is caused by the same atmospheric refraction and scattering effects which produce the red sunset. Green flashes are enhanced by atmospheric inversions, which increase the density gradient in the atmosphere, and therefore increase refraction. Here at Ascension Island there is a very persistent temperature inversion in the atmosphere, generally at between 5000 and 8000ft above sea level.

If the horizon is relatively clear as the sun sets, I can think of few better places to look for a green flash, though even here the event is rare.  A word of caution though, try not to look at the sun until it is just on that last point of setting.

Issued by C Hill at  1500Z 13^th July 2009

Met Office Ascension

Contact Met Office Tel 00247 3317

Email: ascensionstaff@metoffice.gov.uk

© Crown Copyright 2009