WATER vapour is invisible with no apparent feel or aroma. But it plays a huge role within the environmental cycle. Without water in the atmosphere weather would not exist, we need water molecules to create weather.

The air can hold huge amounts of water, especially when the temperature is high, this is why we can experience torrential downpours in summer when the air temperature is highest. Warmer air has a greater capacity to hold water than cold air, allowing it to hold much more water before it becomes saturated. When moist air becomes cooler it eventually becomes saturated. When the air becomes saturated, the water vapour will condense into water droplets, producing fog or cloud, the area where this first takes place within a cloud is the base, which is called the condensation level. To seek out how moist the air is you need to measure its relative humidity (the amount of water in the air). Saturated air has 100% relative humidity. Relative humidity tends to increase at night as the temperature falls and decrease by day as the air warms.

The instrument for measuring relative humidity is called a hair hygrometer or hygrograph, the latter records the change in relative humidity on a graph which runs for a whole week, this form of recording allows the observer to witness the rise and fall of the moisture in the air over a period of time. Next Week.....December Weather.

Glossary: Humidity: The amount of water vapour present in a volume of air. Relative humidity is the amount of water vapour as a percentage of the maximum amount a given parcel of air can contain. Weather for week Monday 1st December-Friday 5th December.

Winds from the north will back to the west later this week from off the Atlantic. Starting off cold and then turning somewhat less cold on Thursday/Friday.

Monday sunshine and a few wintry showers, overnight frost.

Tuesday sunshine, local showers.

Wednesday some rain or sleet with wet hill snow.

Thursday and Friday less cold and varied weatherwise.

Maximum temperature 6-9c 43-48f.

Minimum temperature Minus 3c at first then by Thursday and Friday 6-7c 43-45f.

Last Week's Observations ( Monday-Sunday) Highest day temperature.............13.0c on Wednesday 26th November.

Lowest night temperature...........Minus 3.7c on Sunday 30th November.

Wettest day...............................3.2 mm on Thursday 27th November.