Air Masses And Fronts: Isobars And Fronts Flashcards
What are isobars?
They’re lines on a weather map which join together places of equal atmospheric pressure.
What should you think about when looking at isobars on the map?
- Atmospheric pressure is measured by millibars
- They’re usually drawn at intervals of 4 or 8 millibars
- The closer together they are, the stronger the wind will be
When do fronts occur?
When 2 different air masses meet
What are the 3 different types of fronts?
Warm, cold and occluded
How are warm fronts formed?
They’re formed when warm air rises over a mass of cold air.
What happens when warm air lifts into areas of lower pressure?
It expands, cools and condenses the water vapour as wide, flat sheets of cloud that bring gentle rain.
How is a warm front shown on a weather map?
Solid red lines with red semicircles.
How are cold fronts formed?
A cold air mass replaces a warmer air mass. The cold air follows the warm air and gradually moves underneath it, pushing the warmer air upwards.
Why does it rain heavily when the colder air is pushed upwards?
This is because as it rises quickly, moisture in the air condenses, forming rain clouds. As the cold front passes, the clouds roll by and the air temperature is cooler.
How are cold fronts shown on weather maps?
Solid blue lines with blue triangles
How do occluded fronts form?
They occur when a cold front takes over a warm front or vice versa. Theses fronts bring changeable weather conditions.
How are occluded fronts shown on a weather map?
Red semicircles and blue triangles positioned next to each other but also both being purple when mixed.
