Fronts and Pressure

Fronts A front is the leading edge of an air mass that is pushing against another air mass.

four types of fronts: The weather symbols for the fronts Cold front What page on the ESRT is this? Cold front Warm front occluded front stationary front

Cold front: brings a cold air mass of air & replaces a warm air mass.

A warm front: brings a warm air mass. Replacing a cold air mass.

FRONTS BRING NEW WEATHER!

WARM FRONTS BRING A WARM AIR MASS (WARMER WEATHER)! COLD FRONTS BRING A COLD AIR MASS (COLDER WEATHER)!

Stationary front: boundary between air masses that are not moving.

Occluded front: when a warm air mass is trapped by cold air on both sides.

What do you notice at all the fronts? IT ALWAYS RAINS WHERE TWO FRONTS MEET!

It always rains when fronts meet because warm air rises, expands and cools forming clouds when they meet a cold front. It is raining at the shaded areas

Where is the WARM FRONT going? (how do you know?) The warm front is moving north-east. The front points where its going WARM FRONT COLD FRONT

Where is the COLD FRONT going? (how do you know?) The cold front is moving east. The front points where its going WARM FRONT COLD FRONT

What is Air Pressure? Pressure – The force or weight of air molecules pushing down on a surface. Weather maps always show areas of high & low pressure Capital H: is a high pressure system. Capital L: low pressure system.

HIGH PRESSURE SYSTEMS: are winds that blow clock-wise & away from a high-pressure center. Draw in the arrows below: H

If the millibars are highest in the middle, it is a high pressure system If it WASN’T labeled, how could you tell this is a high pressure system?

Hurricanes and tornadoes: form over warm and moist air (mT)

1st.Hurricanes start over the warm moist water (mT) in the Caribbean. The typical path for hurricanes in North America: 1st.Hurricanes start over the warm moist water (mT) in the Caribbean. 2nd. Move towards Florida. 3rd. They are deflected towards the North-eastern United States by the westerlie winds.

WHY SHOULD WE CARE ABOUT PRESSURE SYSTEMS? SO WHAT? WHY SHOULD WE CARE ABOUT PRESSURE SYSTEMS?

Pressure systems help us to predict the weather. High pressure brings cool clear weather. So if the air pressure is increasing, cool clear weather is coming. Low pressure brings warm & rainy weather. So if air pressure decreases, bad weather is coming. A good way to remember: Happy Highs Lousy Lows

H L H H L