Definition of weather
The state of the atmosphere at a particular place and time as regards heat, cloudiness, dryness, sunshine, wind, rain, etc.:
Temperature
A hot day
in Summer.
When we take a temperature, we are measuring how hot or cold it is. We measure the temperature using a thermometer. We change our clothes based on the temperature. Farmers use the temperature to know when to plant their crops and pilots use this to know whether to de-ice their planes.
Did you know?
The weather you see on the weather forecast is the temperature in the shade.
A cold day in Winter
Rainfall
When people watch the weather forecast, they want to know how hot/cold will it be and will it rain? Rain is measured using a rain gauge.
Precipitation is any form of moisture falling to the ground. It can be either: rain, sleet, hail, snow, freezing rain.
Did you know?
In the English language, there are ten different words for rain but the Inuits, living in the frozen North of Canada have over 50 words for snow.
Source: Jan Hetman / Shutterstock
Heavy snow
Heavy rain
Heavy hail
Wind speed and wind direction
a Calm day
a Windy day
Wind speed is measured using an anemometer and it can be measured in kilometers per hour / miles per hour or metres per second. The wind direction is measured using a weather vane and the four points of the compass. Knowing the wind direction is important because it helps give us clues as to what sort of weather is coming. A wind from the north in the northern hemisphere would be cold, and a wind coming from a sea or ocean would be moist, with potential for rain.
A hand held anemometer used to measure wind speed.
A weather vane used to measure wind direction.
Cloud types and cloud cover
Did you know?
Some clouds can be 10 kilometres high and the fastest clouds move at speeds in excess of 160 km per hour.
How many different cloud types can you spot in this cloud montage? Identifying clouds can give you an indication of what weather is coming.
Some of the different cloud names are: cumulonimbus, stratus, cirrus and cumulus.
Cloud cover is measured in eighths or oktas and uses this scale seen below.
Visibility
Fog
Visibility refers to how far we can see and it is important for transport users, namely, car drivers, ship captains and airline pilots. When it is very foggy, the weather agencies issue weather warnings.
Visibility can be reduced by air pollution but also, sandstorms, forest fires, blizzards and thunderstorms.
Did you know?
In the Arctic, the visibility is often very good and it can reach as far as 100 km.
Smog
WHAT IS WEATHER?
