Weather and climate

Weather is the day-to-day state of the atmosphere: temperature, precipitation, wind, cloud and sunshine. Climate is the average weather over a long time, usually 30 years.
Instruments: thermometer (temperature), rain gauge (rainfall), anemometer (wind speed), wind vane (wind direction) and barometer (air pressure).
A climate graph shows rainfall as bars and temperature as a line.

Types of rainfall

Relief rainfall: moist air is forced to rise over hills or mountains, where it cools and condenses into cloud and rain. The sheltered side is a drier rain shadow.
Convectional rainfall: the sun heats the ground, the warm air rises quickly and cools, forming thunderstorms, especially in summer.
Frontal rainfall: warm air meets cold air and is forced to rise over it.

High pressure (an anticyclone) has sinking air, clear skies and dry weather: hot sunny days in summer, and frosty or foggy mornings in winter.
Low pressure (a depression) has rising air, cloud, rain and strong, changeable winds.

The UK and the Channel Islands have a temperate maritime climate: mild, wet winters and warm summers.
The North Atlantic Drift, a warm ocean current, keeps them milder than other places at the same latitude.
The prevailing winds come from the south-west, off the Atlantic, so western areas are wetter than eastern areas.
A microclimate is the climate of a small area, such as a sheltered playground.

Weather: The day-to-day state of the atmosphere.
Climate: The average weather over a long time, usually 30 years.
Precipitation: Water falling from the sky, such as rain, snow or hail.
Anemometer: An instrument that measures wind speed.
Barometer: An instrument that measures air pressure.
Relief rainfall: Rain caused when moist air is forced to rise over high ground.
Convectional rainfall: Rain caused when the sun heats the ground and warm air rises quickly.
Frontal rainfall: Rain caused when warm air rises over cold air.
Rain shadow: A drier area on the sheltered side of hills or mountains.
Anticyclone: An area of high pressure, bringing settled weather.
Depression: An area of low pressure, bringing cloud, rain and wind.
Prevailing wind: The direction the wind blows from most often.
Microclimate: The climate of a small area.