RENDLESHAM WEATHER STATION | FREE LEARNING CENTRE

Volume 1: The Atmosphere

Lesson 1.1: What is the atmosphere?

Earth is surrounded by a mixture of gases, mostly nitrogen and oxygen. The lowest

layer, the troposphere, contains almost all everyday weather. It is usually about 8–18

km deep, varying with location and season. Sunlight warms the ground, which warms

the air above it.

Try it: Watch the sky at breakfast, lunchtime and evening. Write down how cloud

cover changes.

Quick quiz: Which atmospheric layer contains most weather?

Answer: The troposphere.

Lesson 1.2: Temperature and humidity

Temperature measures how warm or cold the air is. Humidity describes water vapour

in the air. Relative humidity is the percentage of saturation at the current

temperature: 80% does not mean the air is 80% water. The dew point is the

temperature at which air would become saturated if cooled without changing its

moisture content.

Try it: Compare temperature and relative humidity readings from your station

morning and afternoon.

Quick quiz: What happens to relative humidity if air warms but its water vapour

stays the same?

Answer: It generally falls.

Lesson 1.3: Why weather changes

Uneven heating creates differences in temperature and pressure. Air moves, rises and

sinks, while water evaporates and condenses. Together these processes produce

clouds, wind and precipitation. Weather describes short-term conditions; climate

describes patterns measured over decades.

Try it: Write a two-sentence description of today’s conditions in Rendlesham, using

your own observations.

Quick quiz: Is today’s rainfall weather or climate?