Weather and climate, Year 8: more practice

Weather

提示It can change from hour to hour.

为什么Weather is short-term. Climate is the pattern of weather over many years.

Thirty years

提示A few decades, long enough to smooth out odd seasons.

为什么A long average stops one unusually cold or hot year from distorting the picture.

Climate

提示Does it describe one day or a long-term pattern?

为什么It describes a long-term pattern. "It is raining in Manchester today" would be weather.

It rises, creating low pressure

提示Warm air is lighter than cool air.

为什么The rising air cools and its moisture condenses, which is why the Equator has heavy, regular rain.

Dry, clear weather

提示Sinking air warms and cannot easily form cloud.

为什么This is why many of the world's great hot deserts, such as the Sahara, lie near 30 degrees.

Air flows to even out the difference in pressure

提示Think of air spreading out from where it is crowded.

为什么The bigger the pressure difference between two places, the stronger the wind.

The sun's rays arrive at a low angle and are spread over a larger area

提示Think about how a torch beam spreads when shone at a slant.

为什么Near the poles the rays are also passing through more atmosphere, so they lose more energy before reaching the ground.

Temperate maritime

提示The sea has a calming effect on temperature.

为什么The sea warms and cools slowly, so coastal places have a smaller range of temperature than inland ones. The warm North Atlantic Drift also helps.

The south-facing side

提示The sun is in the southern half of the sky.

为什么The direction a surface faces is its aspect. Aspect is one reason microclimates differ over short distances.

The walls give shelter from the wind and store heat

提示Think of what a barrier does to moving air and to sunshine.

为什么Shelter reduces wind chill, and brick or stone soaks up warmth by day and releases it slowly at night.