All Things Weather Wise Weather Instruments Pressure Systems

All Things Weather Wise Weather Instruments, Pressure Systems and Fronts

Warm Up 1. 2. 3. What is air pressure? What happens to the molecules when air warms up? Why does air move out of a filled balloon when you untie the end?

Warm Up 1. 2. 3. 4. 5. Why is it hot at the equator and cold at the poles? What is needed to create an area of high pressure? What causes low pressure? What happens to air at the poles? At the equator? What is wind?

Warm Up 1. 2. 3. 4. What type of clouds are associated with good weather? How is weather described? List 7 factors. How do clouds form? Describe a convection current.

Warm Up 1. 2. 3. 4. 5. What causes low pressure on the Earth’s surface? What type of weather is associated with a cold front? What is wind? What causes it? Which way does air move? What is the role of ozone in the stratosphere? What happens to temperature in the troposphere?

What Is Weather? …Conditions of the atmosphere at a given place and time. l Air pressure l Temperature l Wind speed, wind direction l Cloud cover, type l precipitation

Weather Instruments: Anemometer l l Measures wind speed Wind turns the cups; faster wind turns cups faster Faster wind = higher wind speed Wind speed measured in mph or kph

Weather Instrument: Barometer l Measures air pressure • When air pressure increases, the air pushes down on the mercury, which then rises in the tube. • Changes in air pressure can help to forecast weather

Wind Sock l l l Wind fills the cone shaped bag Tells the direction of the wind Always name winds by where they are blowing FROM - A southeast winds blows from the southeast

High Pressure System l Cooler, sinking air l Creates generally clear days, good weather l May be small cumulus clouds, if any

Low Pressure System l Warmer, rising air l Stratus clouds form if there is enough moisture in the air l Drizzle or rain may occur

Warm Front l l When a warm air mass overtakes a cooler air mass Warm air rises over cool air Light to moderate, but steady rain at frontal boundary Temperature increases after front passes

Warm Front

Cold Front l l Cold air mass overtakes warmer air mass Cooler air nudges under warmer air Heavy, short periods of showers at frontal boundary Temp drops!

Cold Front

And Just a Bit About Hurricanes l l Form in the tropics over water that is greater than 79 degrees Fahrenheit Gathers strength as it remains over sea A storm must have winds of 75 mph to be considered a hurricane; otherwise, it’s just a tropical storm or depression As it makes landfall, storm weakens, but can still have disastrous effects

Eye Hurricane - A low pressure system where winds blow counterclockwise

Warm Up Draw a Venn diagram comparing warm and cold fronts. Include at least two differences and two similarities.

Warm vs. Cold Fronts Warm l Warm air rises slowly over cold l Stratus clouds form l Moderate precip over a long time Cold Both • Change the l Warm air rises air temp quickly • Occur when l Cumulonimbus air masses l Thunderstorms meet • Happen lover can include lightning land or water and hail and • Can happen tornadoes anytime