Middle school year 3 · second unit
Weather and Climate Change
Whether it will rain today, and how much warmer the Earth will be in a hundred years: both happen in the thin layer of air round the planet. Move by hand how air warms and cools, takes up water vapour and gives it back.
It gets colder up a high mountain. And if you keep going?
A board to adjustYou might expect it to get colder for ever, but it does not. Take the balloon and drag it up to 100 km.
The Earth is said to be warming. By how much?
A board to adjustSee what the carbon dioxide in the air does. Drag the knob on the scale to change its level.
Drops form on the outside of a cold glass
A board to adjustIt did not leak from the glass. It is water that was hidden in the air. Cool the air in the jar.
On the shore the wind blows opposite ways by day and by night
A board to adjustWhy does the wind blow, and why does it turn? Take the sun and drag it up and down.
After a sudden downpour it turns chilly
A board to adjustTwo bodies of air of different character have met. Drag the gold handle to move the front across our town.
What to take away from this unit
- The atmosphere is divided by how temperature changes into the troposphere, stratosphere, mesosphere and thermosphere. Weather happens in the troposphere, and the ozone layer in the stratosphere blocks ultraviolet.
- The Earth keeps its average temperature by giving out as much energy as it receives from the Sun (radiative equilibrium). Greenhouse gases sending part of that heat back to warm the surface is the greenhouse effect; the rise in temperature as those gases increase is global warming.
- The most water vapour air can hold is the saturation amount, greater the warmer the air. Relative humidity = actual vapour ÷ saturation amount × 100. The temperature at which drops begin to form is the dew point.
- As air rises it expands and cools, and when it falls below its dew point the vapour turns to droplets and a cloud forms.
- The push of the air is air pressure. Wind blows from high pressure to low. Because land and sea warm at different rates, there are land and sea breezes and monsoons.
- Where air masses of different character meet is a front. A cold front brings showers in a narrow belt; a warm front brings light rain over a wide area.