Presentation on theme: "What is Weather? Energy is transferred between fast-moving molecules and slower-moving molecules CONDUCTION – transfer of energy when molecules collide."— Presentation transcript:
1 What is Weather?Energy is transferred between fast-moving molecules and slower-moving moleculesCONDUCTION – transfer of energy when molecules collideCONVECTION – occurs when warm air rises and cool air sinks; it’s the transfer of heat, usually in liquids or gases
2 What is Weather? State of the atmosphere at a specific time and place Includes such conditions as air pressure, wind, temperature, and moisture in the airTemperature is a measure of air molecule movementSun’s energy causes air molecules to move rapidly; temperatures are high and it feels warmWhen less of the Sun’s energy reaches air molecules, they move less rapidly and it feels cold
3 You might pick heat or sun….but another good choice would be If we were to pick one term to help explain why we have weather, what do you think would be a good word?You might pick heat or sun….but another good choice would beConvection
4 After the atmosphere is warmed by radiation and conduction, the heat is transferred throughout the atmosphere by convection.Since warmed air has more space between the molecules, it’s less dense and risesCooled air is more dense and tends to sinkIn general, air near the equator tends to rise and air near the poles tends to sink
6 Notice the band of clouds around the equator ? This is the ITCZ or inter tropical convergence zone
7 Why do you think there is this band of clouds near the equator?
8 Did you figure it out? Warm, moist air in the tropics rises Cold air can hold less moisture than warm airAs the moist air rises, it condenses and forms clouds!
9 Now What?Ok, so we know that the weather moves around on these highways and that warm air rises and cold air sinks.But why is it sunny one day, and rainy the next?
10 Let’s take another look at the weather map Notice that there are H’s and L’s on the mapThere are also blue lines with spikes and red lines with half circlesLet’s take a closer look!
11 AIR PRESSURE Air weight that varies over Earth’s surface Warmer air is less dense and exerts less pressureCooler air is more dense and exerts more pressure
12 High Pressure AreasWhen cooler air sinks and is warmed, the air can hold more moistureThis usually means sunny skiesWinds tend to move clockwise around a high
13 Low Pressure AreasWhen warm air rises and is cooled, the air can not hold as much moistureOften, these areas are associated with precipitation and stormy weatherWinds tend to move counter clockwise around the low
14 So, if you see a big H on the weather map over the area you live, you can expect fair weather
15 When you see a big L in your area, there will probably be stormy weather
16 These highs and lows move more or less along the jet stream and bring us our weather changes