How can weather data be presented?

You need to be able to both draw and interpret weather maps (synoptic charts) and climate graphs.

Synoptic Charts

Weather maps use standard symbols to show a variety of weather data. The information you need to read these charts can be found in the key. Here are the standard symbols used on weather charts:

Synoptic charts also show isobars. These are lines joining points of equal pressure. Remember: pressure is measured in millibars. The pressure readings are shown on the isobars as numbers.

You also need to know about isohyets (which join points of equal rainfall) and isotherms (joining points of equal pressure).

The Met Office pages about synoptic charts can be found here. They offer a very clear summary of the topic, with some activities to complete.

Climate graphs

Climate graphs show temperature and rainfall for each month of the year in a given location.

Rainfall is shown as blue bars (a bar chart).
Temperature is shown as a red line (a line graph).


When interpreting a climate graph, make sure you are reading from the correct axis as there are two different vertical scales, one on each side of the graph.

When plotting a climate graph, make sure that the temperature plot is placed in the middle of the month.

There is a superb living climate graph interactive activity here. Its in two parts - you have to finish the first one to gain access to the second. Thanks to Russel Tarr for making and sharing this activity.

Introduction to weather and climate

Today's objectives were as follows:

- To be able to define the terms weather and climate.
- To know the names of the key components of weather.
- To know the names of the key weather instruments.

Weather is the short term state of the atmosphere over a small area. By contrast, climate is the 'average weather', usually taken over a period of 30 years, for a larger area. It considers long term trends.

You need to be able to define the following aspects of the weather, know how they are measured, and give the units of measurement:

- precipitation
- temperature
- air pressure
- cloud cover
- wind speed
- wind direction
- visibility

Precipitation means water falling from the sky in any form eg. rain, sleet, snow, hail. It is measured in millimetres using a rain gauge.

Temperature means how hot or cold it is. It is measured in degrees, using a thermometer.

Air pressure is how 'heavy' the air is. It is measured in millibars using a barometer.

Cloud cover is how much of the sky is hidden by clouds. You use your eyes to measure cloud cover. Cloud cover is expressedin oktas - one okta cover means that one eighth of the sky is obscured by clouds.

Wind speed is how fast the wind is blowing, and it is measured using an anemometer. As you will know from our fieldwork in the lesson, it can be given in a variety of units eg. miles per hour, kilometres per hour, metres per second, knots.

Wind direction is which direction the wind is coming from - it is measured using a weather vane and given as a compass direction eg. north, south, east, west.

Visibility means how far you can see. It is measured using a lightmeter, and usually given in metres.