Climate observations - vapour pressure

Although this resource deals mostly with national average climates, it is important to take into consideration the geographical variations in climate that occur across countries. A national average may not be very appropriate when considering countries that include different climate regimes, strong contrasts in orography, etc. Maps are included here to show the geographic variations.

The maps on this page show the 1961-1990 average annual and seasonal vapour pressure across this country or region from the CRU TS observations (New et al., 1999). For the seasons, DJF = December to February, MAM = March to May, JJA = June to August, and SON = September to November averages.

The gridded data, including timeseries of monthly values for each 0.5° grid cell, and the underlying station data, are available in scientific formats from here and via a convenient Google Earth interface here.

National average 1961-1990 vapour pressure normals for each month of the year are shown in the table and figure below. Seasonal and annual values are also given.

Click for larger image

1961-1990	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Vapour pressure	2.5	2.6	3.4	4.8	7.0	10.2	12.6	12.1	9.3	6.6	4.4	3.0	hPa

1961-1990	MAM	JJA	SON	DJF	Annual
Vapour pressure	5.1	11.6	6.8	2.7	6.5	hPa

Data files

National-average 1961-1990 CRU TS observed normals can be downloaded:

• Temperature, csv format