It can get quite damp and soggy at Woodlands View during all times of the year. Being so high up we often find ourselves in the fogginess of low-lying clouds, and Wal says that it is the only place that he knows where it sometimes rains upwards! According to the Met Office we receive between 1500-2000mm of rain per year on average, although it often feels like quite a lot more.

 

Rain and drizzle are the commonest form of precipitation (water falling from the sky) that we get at Woodlands View. Drizzle is defined as water-droplets that are smaller than 0.5mm across, and it tends to drift down from low-level stratus clouds. Raindrops are obviously larger- up to 6mm and can fall at speeds between 2- 20mph2.

 

Rain is formed when warm, moist air rises and then cools, condensing to form clouds and then possibly falling as rain. Around Woodlands View the warm moist air from the Atlantic is forced up over the Pennines by prevailing South Westerly winds, where it then cools and condenses. The air gets approximately 1 oC colder for every extra 100m altitude.This is one of the reasons why we get so much rain or other types of precipitation such as snow. Rainfall made in this way is known as ‘Orographic' or 'Relief' rain.

Diagram

 

Another way of producing rain is when a warm air mass meets a cold air mass. Warm air can hold more moisture than cold air and this lower density warm air gets forced up above the denser cold air. It then cools down and the water vapor condenses out to form clouds and then rain. This is known as ‘Frontal rain’ as the two air masses are known as a ‘warm front’ and a ‘cold front’.

 Diagram

 

Convectional rainfall  is the process that gives us 'sunshine and showers' and it is more predominant in the South and East of the country where it is generally warmer, especially during the summer months. It is responsible for the heavy showeres and thunderstorms that can occurs in those parts of the country.

Rain clouds are known as Nimbo- or –Nimbus, from the Latin for rain cloud, and come in several different types. Not all rain clouds are the same!

 

The low clouds that often hang damply above or around Woodlands View are Stratus. These are the lowest level clouds and can appear as mist or fog, even in the valleys and are fairly common around here in autumn and early winter. They usually provide plenty of drizzle, or in the depths of winter we get small grains of snow. The clouds are a dull greyish white, fairly featureless and rather gloomy.

 

Cumulonimbus clouds are big towering rainclouds. Their name means ‘heaped rain cloud’ in Latin. Their appearance in the sky above Woodlands View means that all outside jobs need to stop pretty quickly as they usually signal heavy rain, hail or thunderstorms. They are amazing to watch, building up into their huge mountainous peaks, and we love trying to photograph the lightning that tears through them. So far we have seen one funnel cloud extending from the base of a Cumulonimbus.

 

 

Nimbostratus clouds bring persistent rain or snow and are thick enough to block out the Sun. They are dark grey mid level clouds that generally cover most of the sky in a featureless layer. Unless they are providing snow they are our least favourite cloud as they just seem to rain… and rain… and rain and then for a change…rain!

 

In winter snow and sleet make regular appearances on the top o’ the hill. There is quite often a clear line half way up the valley where the snow suddenly starts. Snow is not frozen rain but is formed from tiny ice crystals that stick together. It needs to be 20C or colder for it to snow, any warmer and the ice crystals will melt to form sleet or rain. Is it ever too cold to snow? No, apparently not, although colder air holds less moisture than warmer air so snow is less likely when it is really cold (such as -400C).

 

Hailstorms are fairly exciting, especially during summer months. Hailstones are randomly shaped pieces of ice that are formed in cumulonimbus clouds. Small frozen raindrops get caught in an updraft inside the cloud and move upwards (convection currents- physics in action). As they do so they get bigger as more water collects on their surface and freezes. Some hailstones can get really large as they move up and down inside the cloud before they finally get heavy enough to fall to the ground. We’ve never had really large hailstones at WV, which is lucky for us, as they can get large enough to damage buildings and property.

 

In spring and summer especially, we observe a number of rainbows. Rainbows are seen when the observer is standing between the rain and the Sun, with the Sun behind them. The sunlight is reflected and refracted as it passes through the raindrop resulting in the beautiful spectrum of colours. This image just shows the primary rainbow but you can get double rainbows too. These have the colours reversed as the light is reflected twice inside the raindrop. Rainbows are an optical illusion and everyone sees their own personal rainbow.

 

 

 

1 http://www.metoffice.gov.uk/learning/learn-about-the-weather

 

2        http://wxguys.ssec.wisc.edu/2013/09/10/how-fast-do-raindrops-fall/

 

3        http://cloudappreciationsociety.org/