Weather

Reading and Q’s What is weather? Define and describe the 6 major weather variables. What causes wind? Why does cold air hold less water? How do clouds form? Draw a picture of the water cycle in your notes.

Warm Up There are 8 grams of water vapor in the atmosphere during the day. The relative humidity is 50% In the night, the temperature drops causing the relative humidity to increase or decrease? If the relative humidity goes over 100% during the night, what will we discover the next day?

Warm Up What was the worst weather related experience you ever had? – Share with your neighbor.

Warm Up Low High What kind of pressure system is this and what will the weather be like?

What is weather? The change in air conditions in a specific place

Describe the 6 major weather variables – Temperature: The amount of heat energy in a location – Air Pressure: The concentration of matter (air and water) and energy (heat) in a specific location – Wind: The movement of air from high to low pressure areas – Humidity: The amount of water in the air relative to the temperature – Dew Point: The point at which water vapor is beyond maximum and begins to condense into liquid or solid

What causes wind? Air moves from high pressure to low. The greater the difference between the high and low areas the stronger the wind will be

Why does cold air “hold” less water? Colder air has less heat energy. This causes the molecules to slow down and move closer together. If the gas water molecules do not have enough energy they will condense into liquid water when contacting pollen or dust in the air.

How do clouds form? When air moves upward into the atmosphere it cools causing water vapor to condense into liquid water droplets that surrounds dust particles in the air forming a cloud. When the droplets get large enough precipitation occurs.

The Water Cycle

What causes the weather to change? Air masses: Large sections of air with uniform characteristics High pressure air masses and low pressure air masses Warm and Cold fronts ZFc ZFc

Describe the air masses

High Pressure High Low

High Pressure High Low High pressure moves out to sides and low pressure comes in from above

High Pressure What will the weather be like? Why won’t the high pressure air move up?

Low Pressure Low High

Low Pressure Low High High pressure air moves in pushing the low pressure air upwards

Low Pressure What is the weather like? Why won’t the high pressure air move down?

Fronts The boundary between two air masses is a front. The air mass that moves is the “front” – Cold air moving towards warm = cold front – Hot air moving towards cold = warm front – The battle/collision on the boundaries of air masses causes significant changes in the weather –

Severe Weather Make a list of what supplies you think you should have in case of a weather based emergency

Severe Weather What should you do before, and during severe weather – Extreme Heat – Flood – Landslide – Thunder/Lightning Storm – Tornado – Wildfire – Blizzard