Weather Watch

Damp or dry? Measuring humidity

Measuring humidity is easier than you might think, especially with modern day instruments.

Humidity is the amount of water vapour, an invisible gas, in the air. Warm air can ‘hold’ more water vapour than cold air; in fact air at 35°C can hold six times more water vapour as air at 5°C. All meteorological instruments measure the relative humidity (RH); this is the amount of water vapour in the air compared to the amount required to saturate it, given as a percentage - so completely saturated air has a RH of 100%.

Temperature extremes in your garden

Taking temperature measurements in your garden is a great way to start investigating microclimates. We take a look at some maximum-minimum thermometers on the market.

Just how cold did it get last night and how hot will it be this afternoon? You can measure these daily extreme temperatures in your own garden using a maximum-minimum thermometer. A variety of thermometers are available in high street stores, garden centres and online, ranging from the traditional to the hi-tech.

Microclimates in the garden

Every garden has a number of different microclimates, and these have an effect on not only the temperature but also the amount of rainfall and wind strength. Even within a small garden, there can be large differences in conditions. If you have been digging or weeding your garden for a while, you will probably have discovered hot, dry corners and cold, draughty spaces. Understanding the microclimates in your garden really gives you a head start. Most gardeners want light and shade, dry and damp, sheltered and exposed areas in which to grow different plants and create contrasting spaces.

Staying safe in the sun: The whys and wherefores of sun protection

It is easy to think of sunburn as something that doesn't really happen in the UK, but it can and it often does. You don't have to be sunbathing to get sunburnt; it may happen while you are playing sport, walking or even working outdoors. To ensure you have fun in the sun either in the UK or abroad, we have put together a sun factfile to encourage you to enjoy the sun safely through the UK summer.

A newly discovered atmospheric optical phenomenon called… Steve

Image: 'Steve' (Source: ESA - Dave Markel)

If Boaty McBoatface is anything to go by, social media has a lot to answer for when it comes to naming things for science. The most recent example of this is Steve; a recently discovered phenomenon all thanks to the power of social media and citizen scientists – something that wouldn’t have been possible 20 years ago. 

Nacreous clouds

Image: Nacreous clouds over Aberdeen on 29th January  
Credit: Stephane Gentile, Associate Fellow of the Royal Meteorological Society

Several rare sightings of nacreous clouds have been reported over the last few days, delighting cloudspotters, with photographs of the clouds coming from England and Scotland.

Dark Lightning

This 'dark opponent' discharges from storm clouds and flings antimatter into space. Astrophysicists and meteorologists are now trying to understand what they have termed ‘dark lightning’. 

Lightning occurs due to charge separation in a cloud. When negatively charged electrons build up at the base of a thundercloud, anything it passes over becomes   positively charged. If the cloud passes over a tall object, like a tall building or tree, these electrons jump, creating the ‘pitchfork’ of light you see streaking across the sky.

Catatumbo ‘Everlasting’ Lightning

It occurs over the mouth of the Catatumbo River where it empties into Lake Maracaibo in Venuzuela, South America. Each year, over 1.2 million bolts of lightning are confined to the mouth of the Catatumbo River - the single highest concentration of lightning in the world.

The Catatumbo lightning, whilst not rare or unusual, is a  remarkable feature in that it persists in the same place night after night. Indeed, the reliability of the storms means that they have historically been used as a maritime navigational aid.