What is a Warm Front?
http://covis1.atmos.uiuc.edu/guide/fronts/warm
A warm air front is the place where a warm air mass replaces a cool air mass. We already know that warm air overrides cold air. This is because the air masses have different temperatures and densities. Warmer tropical air is forced over the cooler polar air. This forms a bulge on the front - called a warm front.
Fronts can be several hundred kilometres in width. The air behind a warm front is warmer than the air ahead of it. If a warm front passed overhead when you were standing outside, then you would feel the air warming up. The air would also be more moist than before.
We are now going to look at a weather map from the Electronic Telegraph web site. This will help us understand how to recognise a warm front.
A Warm Front Over the UK on the 21st January 1998
http://www.telegraph.co.uk |
This chart shows the progression of a warm front
over the UK on the 21st January 1998. The front is the black line with the oval
lumps on it. It travels in the direction of the wind - in this case north
east. You can see that the weather conditions ahead of and behind the front are
different.
We said before that the temperature ahead of the warm front is usually colder than the temperature behind the warm front. We can see the difference on this map.
What is the change in temperature ahead of and behind the warm front?
What other weather conditions change ahead of and behind the front? |
Do you think that you would now be able to find a warm front on a map? If you do then look at the map below. If you don't, then carry on with this tutorial.
Quiz
The following map shows two locations where there might be a warm front over the UK. The white numbers are the air temperatures in degrees Celsius. Use the information on air temperatures given above to work out which line represents the warm front.
Two Possible Locations For a Warm Front
We can now look at some of the data collected from the ECN sites around the country. This will help you understand the changes in weather as the front passes over.
Alternatively, would you like to look at more information about the ECN?
