Investigating evaporation

What makes water evaporate faster?

Wind, warmth and a large surface all speed up evaporation.

Four factors

Four factors change how fast water evaporates. Temperature: warmer water evaporates faster. Wind: moving air carries water vapour away. Surface area: a wide dish evaporates faster than a narrow one. Humidity: dry air takes up more water vapour.

Washing hung out on a hot, dry, windy day with clothes spread out dries fastest – all four factors help at once.

Planning a test

Choose one factor to test, for example surface area. Put the same volume of water in containers of different widths. Keep the place, temperature and starting volume the same.

Containers should be put side by side, so they get the same sunshine, wind and temperature.

Measuring

Measure the water left each day with a measuring cylinder. Read the scale at eye level. Record the volume in a table, then draw a line graph.

The steeper the line on the graph, the faster the water is evaporating.

Monsoon and winter

In the monsoon the air is very humid, so clothes dry slowly. In the dry winter months, things dry much faster.

Many families dry clothes under a fan or near a window in the monsoon, because moving air helps carry away the water vapour.

What I learnt

I know the factors that affect evaporation.
I can plan a fair test and present results in a line graph.