Donna (7) asks “Where do clouds come from?”

Donna, many thanks for the question. Before trying to answer it I thought I would ask my team a question.

Donna, what do you think about the puddles question? Think about how you would answer it and then go to my answer to a previous question.

Now to your question. Firstly I have created a little animation to show how the puddle disappear. You have to imagine that the shapes are water particles (molecules is the proper word). In the puddle they are all moving around. Most of them like being with the other particles BUT some are just moving around a little bit too fast and manage to escape from the puddle. When the Sun begins to warm the puddle it makes more water particles move around faster and more escape. This goes on until the puddle disappears.

 

The water particles are very small and are are lifted by the air up into the sky. High above the ground the air is quite cold so the water particles ‘slow down’. When they are moving ever so slowly if they meet another water particle they join up with each other and form droplets of water. This is how a cloud begins to form.

At home look at the steam from a kettle, BE VERY CAREFUL AND CONSULT AN ADULT.  At the exit of the kettle spout you can see nothing, BUT just above this the hot water particles begin to cool down and slow down and reform clouds of water.

(revised 21/4/17)

Niamh (10) asks “How do scientists know what the weather is going to be like in the future?

Niamh, that is a question that I have asked several times over the last 20 years ….. and the answers have changed. I asked my team about their thoughts.

Niamh, the weather forecasts were initially based upon previously recorded weather patterns. Records of the what happen to the weather go back to the 19th century  and the weather experts of today look for patterns in past weather to predict what is going to happen in the future.

All the past patterns have now been computerised so part of the role of the forecasters is to get the computers to analyse the patterns and then make suggested predictions.

Nowadays the weather experts ( they are called meteorologists) also have satellite images  to help them predict the weather. They also use other sensors like weather balloons which record air pressure and temperature at different levels in their location.

Niamh, for the distant future it is very difficult to predict what the weather will be like. The weather is one of those magnificently independent variables that we still cannot control.

Niamh if you or any other reader would like to make a comment please go to the Leave a Reply box below. Or ask another question.

Why do we have droughts? asks Lisa (10)

It is a difficult question to answer. There are a lot of possible things that could cause a drought, however one of the most interesting is the effect of atmospheric pressure.

If you listen to weather forecasts you would have heard of a low and high pressure areas. You might have also noticed a pattern. When the weather forecast talks about low pressure it is normally accompanied by rain while high pressure is accompanied by sunny periods and dryness. Dryness over a long period of time could mean the loss of a lot of ground water and therefore create a drought. You get long periods of high pressure over deserts,

So why does this happen?

When you have high pressure dry air descends from the colder air higher in the atmosphere (cold air is more dense and heavier than warm air. In low pressure the movement of the air is in the opposite direction with the warmer, ground level air rising carrying with it water vapour which eventually forms clouds as it gets colder.

Lisa, there are some difficult ideas here. Think about them and then ask another question.That’s the way science works.


Revised (03/02/17)

Elizabeth (9) asks “How does sand form in a desert?”

I agree we need to do an investigation.  The suggestion is that the desert sand might have come from the soil. Let’s see if we can find sand in the soil around us. Before we do this lets think about soil, the soil in your garden. What do you think it is made of? Maybe it is just made of soil? Maybe it is made of a mixture of things? Let’s investigate these questions.

Collect some soil. Get a plastic transparent beaker or a jar with a lid. Put a couple of small spoonfuls of your soil into the container. Add enough water so that it is half full. Cover and shake for about 20 seconds. Put it down and wait for about fifteen minutes. Now look at it and make notes on what you see. Repeat with another sample and another beaker or container (investigations always need to be checked).

Has your experiment resulted in layers of stuff in the beaker? Maybe a bit like the layers in the image below.

If it has then think about why you have layers? What has formed the first layer and why? Was it because it was the lightest or heaviest ‘stuff ‘ in the jar (soil)? Is the second layer made up of ‘stuff’ that is lighter or heavier?

The bottom layer is ‘sand’ …..the heaviest ‘stuff’ that makes up soil. The other layers are ‘silt’ and ‘clay’. Look at the diagram that my friends have given you the sand particles are the biggest.

Now to deserts. In very arid (dry) conditions the soil dries out. The wind basically blows away the smallest particles of clay and silt leaving the largest so a desert of sand is formed.

Elizabeth … thank you for your question.

How strong is a thunderstorm? -asked Jessica (8)

thunderclouds

Many thanks for your comments team. Yes you are right, to create a thunderstorm you need a lot of warm water. It’s development goes by the following crude set of stages …

  • Lots of warm water evaporates (turns from a liquid state into a gaseous state.). Thunderstorms are therefore more common in the warmer regions of our planet.
  • The gaseous water is forced upwards by the warm sea. The warm sea warms the air close to it. This air expands and is therefore becomes ‘lighter’ and moves upwards carrying the water vapour (water vapour is the term used to describe gaseous water) with it.
  • As the gaseous water rises it gets colder (more distant from the warm sea) so it becomes water again (small drops of liquid water). A cloud begins to form.
  • The heat from the ocean continues to make the water and water vapour(clouds) rise.
  • It gets even colder and more of the water vapour turns back to water.
  • Some of the water droplets in the cloud turn into ice particles.
  • The ice particles separate some move to the top of the cloud others remain in the bottom.
  • This split causes an uneven distribution of electrical charge in the cloud.
  • The result is Lightning and Thunder.
  • Some of the frozen water falls away from the cloud. this causes all sorts of down draughts and strong winds are created.
  • Some of the ice does not melt as it falls through the air – this forms hailstones.

You could look at this question http://www.sciencemaster.co.uk/2016/11/18/elizabeth-9-asked-a-question-on-lightning/

 

Any questions, please leave them in the `Reply Box’

Marcus(11) asks – ‘How do tsunamis form?’

tsunami

They seem to have left me to finish off.

You could try to create your own Tsunami. In a tank of water drop a pebble and look at the small waves that are created. Then (in an area where water on the floor is not a problem), drop a brick into the tank and look at what that creates. This movement of water becomes larger when the wave reaches the shallow areas (beaches) of the surrounding area. It gets bigger, faster and more powerful. Look at the excellent video below.

Elizabeth (9) asked a question on lightning

Elizabeth, thank you for your question. “How many %C is the air surrounded by lightning?” I am sorry that I had a difficulty in understanding it. Are you asking about the temperature (degrees C) or are you asking about the Carbon (C) in the air ?  As it was a question about lightning I thought I could ask my friends to talk about that. If you want to revise your question you can easily ask it again. lightning-strike

Thanks team, some very interesting observations.

What I find interesting is how does lightning happen. It’s all about clouds. Hot weather produces lots of evaporation of water from our oceans. The hot air and water mixture rises, look at the clouds from a kettle. As it rises, the cloud of water vapour and air gets colder, and colder. The water turns into very small ice crystals which are still lifted by the cloud of air that they are in. As this happens it is thought that the ice particles separate ……. the lighter particles move to the top of the cloud while the heavier particles remain at the bottom.

The water/ice particles have a small electrical charge associated with them. When they separate the charge moves with them. It is likely that this causes an uneven redistribution of the total electrical charge. If you have more lighter water/ice particles at the top of the cloud than heavier ones at the bottom the difference in the total charges could be significant. So ‘flash’ they try to equalise and thus the lightning flash. It’s the process of the ice crystals at the top of the cloud trying to get rid of their excess electrical charge by giving it to the heavier ice crystals at the bottom of the cloud.

Sometimes difference in charge is so great that the ‘flash’ continues to the ground, but if you are in a storm and look at the flashes a lot of them are within the clouds themselves.

Elizabeth, sorry for such a long explanation. It was such an interesting question. If you have any other questions linked to what my friends and i have said please ask them.

Elizabeth. Some additional information ……. Look at this site. The type of electricity that is built up in clouds , before the lightning flash is static electricity. There are some experiments you could try.

(added 20/11/16