What this lesson teaches
I can read maps, graphs, photographs and texts, and separate what they show from what they suggest.
Syllabus K229, Topic 1.3, Key Question 4 (part). How to present findings?
Make a guess
A weather report says a north-east wind is blowing over Singapore. Which way is the air moving?
- From the south-west towards the north-east.
- From the north-east, towards the south-west.
- Round in a circle, changing direction every hour.
- Straight up from the north-east coast.
Show the answer
From the north-east, towards the south-west.
Winds are named by the direction they come from. A north-east wind comes from the north-east and blows towards the south-west.
A wind rose shows how often wind came from each direction; wind speed needs a separate key.
Winds are named by where they come from. A north-east wind blows from the north-east towards the south-west.
A wind rose groups observations by compass direction. Read the key. In this practice rose, spoke length shows a count, not speed.
There are 30 made-up observations: N 3, NE 12, E 5, SE 1, S 2, SW 4, W 2 and NW 1. North-east is most common: 12 / 30 x 100 = 40%. That does not mean the wind was always from the north-east.
Some wind roses use colours for speed, or show calm periods separately. This one has no speed data and leaves out calm periods. So it cannot tell you the top wind speed.
- Wind direction
- Named by where it comes from.
- Spoke length
- How often wind came from that direction.
- Speed
- Only shown if the key includes it.
Step by step
Read the key
Does length show counts or %? Do colours show speed?
Name the direction
Where the wind came from.
Work out the share
Count / total x 100.
Worked example: Know the limits
You can say north-east was the most common direction in this sample. You cannot say it is the main wind for the whole year without a longer record.
Watch out for this
The longest spoke shows the fastest wind.
Spoke length shows how often. Speed must be shown separately in the key.
Check your understanding
What does the north-east spoke of 12 mean in the practice rose?
- On 12 days of the year the wind blew towards the north-east.
- The north-east wind reached a speed of 12 km/h.
- Twelve observations had wind from the north-east.
Show the answer
Twelve observations had wind from the north-east.
Yes. It is a count of how often.