Weather Vocabulary

Weather The happenings in the atmosphere at a certain time.

Global Pattern A global pattern is something that affects the entire world. It is a pattern that is seen throughout the world. Weather patterns are examples of global patterns. Climate has global patterns. These are systems that are important because they affect our entire planet.

Atmospheric Movement This is the large scale movement of air throughout the atmosphere. This movement, by air currents, is how heat is distributed all over our planet.

What are Air Masses???? Large areas (blobs) of air that have the same weather, temperatures and humidity Weather changes occur with changes in air masses

High Pressure System In a high atmospheric pressure system the atmospheric pressure of the air is higher than that of the air around it. (It’s less dense) High atmospheric pressure systems are marked by an H on a weather map They mean clear weather.

Low Pressure System In a low atmospheric pressure system the atmospheric pressure of the air is lower than the air around it. The air is more dense. Low atmospheric pressure systems are symbolized by an L on a weather map. They mean storminess and precipitation

Front- This term is not on your vocabulary page Front- This term is not on your vocabulary page. However, you should add it and are expected to know the definition A place where two air masses of different temperatures meet.

What Do Fronts Do??? They bring changes in the weather (from west to east) Fronts are named for the air that is behind them

Cold Front Cold dense air pushes warm air out of the way Cold fronts move very quickly and bring short periods of rain/thunderstorms Lower temperatures are behind the front SYMBOL – the direction of the “arrows” points towards the direction the front is MOVING

Cold Front Diagram

Warm Front Warm air moves up the cold front as it slowly displaces the cold air Warm fronts move slowly, and bring many days of steady precipitation Higher temperatures are behind the front SYMBOL – direction of “half-moons” is the direction the front is moving

Stationary Front The air from the warm front and cold front meet, but do not move These fronts have the same weather as warm fronts SYMBOL – warm and cold fronts are moving in opposite directions, thus making a stationary condition

Occluded Front An occluded front is a weather pattern. It happens when a cold front overtakes a warm front capturing the warm air between two cold air masses. Usually produce light rain or other precipitation

Let’s see it on the map! Stationary Front Cold Front Warm Front

What is El Niño ? El Niño is an abnormal warming of surface ocean waters in the eastern tropical Pacific.

Normal Conditions Strong winds blow from the east along the equator, pushing warm water into the Pacific Ocean

Normal Conditions The different water temperatures of these areas effects the types of weather these two regions experience. In the east the cool water cools the air above it, and the air becomes too dense to rise to produce clouds and rain. In the western Pacific the air is heated by the water below it, increasing the buoyancy of the lower atmosphere thus increasing the likelihood of rain. This is why heavy rain storms are typical near Indonesia while Peru is relatively dry.

El Niño Conditions An El Nino condition results from weakened trade winds in the western Pacific Ocean near Indonesia, allowing piled-up warm water to flow toward South America.

El Niño Conditions This flattens out the sea level, builds up warm surface water off the coast of South America, and increases the temperature of the water in the eastern Pacific.

El Niño Conditions What happens to the ocean also affects the atmosphere. Tropical thunderstorms are fueled by hot, humid air over the oceans. The hotter the air, the stronger and bigger the thunderstorms. As the Pacific's warmest water spreads eastward, the biggest thunderstorms move with it.

El Niño Conditions The clouds and rainstorms associated with warm ocean waters also shift toward the east. So, rains which normally would fall over the tropical rain forests of Indonesia start falling over the deserts of Peru, causing forest fires and drought in the western Pacific and flooding in South America.

El Niño Conditions The Earth's atmosphere responds to the heating of El Niño by producing patterns of high and low pressure which can have a profound impact on weather far away from the equatorial Pacific. For instance, higher temperatures in western Canada and the upper plains of the United States, colder temperatures in the southern United States. The east coast of southern Africa often experiences drought during El Nino.

Thunderstorms Small area storms formed by the strong upward movement of warm, moist air Usually occur ahead of a cold front as the colder, denser air shoves the warmer air upward This movement of air forms the cumulonimbus clouds that produce thunderstorms These storms are accompanied by heavy rain, thunder, lightning, sometimes hail, and can also produce tornadoes

All thunderstorms produce lightning Lightning is the discharge of huge amounts of static electricity (think of walking across a carpet in your socks and then touching something-ZAP) Thunder is the result of the air quickly expanding from the heat of the lightning bolt You cannot have lightning without thunder!!

Thunderstorm formations – Form SEVERE storms and tornadoes! THIS IS ONE BIG STORM SYSTEM!

Tornadoes Form from very powerful thunderstorms (cumulonimbus clouds) These are funnel shaped columns of spiraling winds that extend down to the ground from the base of a cloud The winds move into a tornado (low pressure), and can reach a maximum of 318 mph! Spin COUNTER CLOCKWISE (like a hurricane) The actual funnel is made by water droplets (clouds) and dust

TROPICAL STORMS                 A tropical storm is the overall name for a storm which is spinning. They form when warm water heats the air causing it to rise really quickly, then it gets pushed aside as it cools. This pushing causes the clouds to spin. . Different names for tropical storms: hurricane typhoon severe tropical cyclone tropical cyclone

HURRICANES Hurricanes are tropical storms where the winds get faster than 118 km/h (73 mph). The storms have a central area of calm known as the "eye", which is the funnel through which the warm air rises. Why are we seeing more of these destructive storms?