The science of drought explained in pictures

Image source, Getty Images

It might seem obvious that there's a shortage of water in the picture.

It is more complex than that from a scientific point of view.

Regardless of whether you look at weather, agriculture or water flow in rivers and streams, there's no single definition of a dry spell.

Government agencies look at how the long dry spell is affecting food production, water supplies and the environment when they declare a "official" dry spell.

Wildlife and water supplies are at risk when rivers and streams shrink. If fields are turned into dust bowls, threats to crops and livestock are looked at.

The flow of water through rivers and the state of the water stored underground are indicators of the severity of the problem.

The drinking water that arrives at our taps is supplied by these.

In southern England and Wales, the rivers are running at very low levels. There are reports of rivers moving downstream.

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For this time of the year, the amount of water stored in the Aquifers is below average.

There is also no water in the caverns. According to the UK Centre for Ecology and Hydrology, at the end of July, the lowest levels of reservoirs in England and Wales had ever been recorded.

Image source, Getty Images

There is a divide between the north and the south. Some parts of northern England and Scotland are escaping the worst of the dry conditions because of the UK's geological make up.

When it rains in the north, the rivers respond much more quickly than in the south.

The dry spell in southern England and parts of Wales is likely to continue for a while. It will take a long time for the river levels to fill up, even if it rains.

The extreme weather will cause smaller harvests, which will make the food we buy in the supermarkets more expensive.

Image source, Getty Images

Scientists will be watching the effects of the dry spell on animals.

Pollution in rivers can affect wildlife.

The link between climate change and heatwaves will be looked at by experts.

In the past the UK has experienced periods of dry weather. It is a normal part of the world's weather cycles.

As Earth moves past the 1.2C of climate change we have seen so far, dry conditions are expected to become more frequent.

The UK has had ten warmest years on record since 1884.

Climate scientists say that the UK's extreme heat in July would not have been possible without human-caused climate change.

Since 1935, July has been the driest month in England.

Warmer and wetter winters and hotter summers are projected in the latest set of simulations.

Water companies and farmers will have to plan how to harvest and store rain in the winter to deal with shortages in the summer.

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