A Rocha Portugal Observatory Report 2009-2010

A Rocha Portugal Observatory Report 2009-2010 85
Rainfall
Rainfall was 89mm lower in 2009 than 2008, but above the average for 2003-2008 which is 542mm
per year (Fig 3). This higher rainfall is mainly caused by the very wet December when 284.5mm fell
across the month. Other than the very large peak in December, the months September, October and
November were lower than average while January had higher rainfall.
Figure 3 Monthly rainfall for 2009 and average rainfall for each month from 2003-2008. To show
variation across different years (2003-2008) error bars are plotted which represent one standard
error.
Wind direction, strength, cloud cover and visibility
The predominant wind direction in 2009 was NW recorded on 52/333 days (15.6%). The second
most common wind direction was N with 37 days (11.1%), while the directions NNE, NE, SE, SW, W
and NNW were all recorded on more than 20 days. In 2008 the predominant direction was NW and
in 2007 it was NE.
The maximum wind speed was on 4 th February and was 4 on the Beaufort scale or 21.7km/h. This
was the only day with a wind speed of 4 on the Beaufort scale out of the 334 days recorded; 3 on the
Beaufort scale was recorded on 15 days.
Predominantly Cruzinha had clear skies (42%) and good visibility (63%). 67/336 days were overcast;
only 30/335 days had poor visibility.