Weather/Meteorology

1. Weather/Meteorology

2. Atmosphere and Heat Energy Video Clip

3. The Atmosphere • 99% of the atmosphere is nitrogen and oxygen. • The remaining 1% is small amounts of argon, hydrogen, carbon dioxide, and watervapor. • ESRT ALERT!! – page 1 gives you this information for free!!

5. The Atmosphere • The amount of nitrogen and oxygen needs to stay fixed, or we would be in trouble. • However, the amount of water vapor is constantly changing…that’s one reason we have weather! • There are 4 main layers to the atmosphere: • 1. Troposphere • 2. Stratosphere • 3. Mesosphere • 4. Thermosphere

7. The Atmosphere • The troposphere is the only layer that contains water vapor, thus it is the ONLY layer that has any weather! • This is why pilots sometimes say they are “flying above the weather” to avoid a storm. They are flying above the Troposphere! • ESRT ALERT!! – Top of page 14has a chart that shows you all you need to know about the layers of the atmosphere! – YES, this means to go there now in your ESRT!!!

9. What can we say about the temperature in each of the layers of the atmosphere? It’s VARIABLE – goes up and down inconsistently What can we say about pressure in each of the layers of the atmosphere? Steadily decreases the higher you go in the atmosphere. Why does it decrease? Because the higher you go, the less atmosphere is above you so there’s less pressure pushing down on you. Using page 14 of the ESRT

10. Ozone Layer Video Clip

11. The Ozone Layer • Ozone (O3) is another important component of the atmosphere. • It is formed when a third oxygen atom (O) combines with an oxygen molecule (O2). • This layer of the atmosphere protects us from harmful ultraviolet light. • Each time chlorofluorocarbons (Cfc’s) are released into the atmosphere, they literally pull apart one oxygen atom from the O3, turning it back into O2. • This has caused massive holes in the ozone layer.

12. Before CFCs were banned, they were used in aerosols, refrigerators, air conditioners in homes, vehicles and businesses, fire extinguishers, insulating foams, styrofoam food packaging, and cleaning and electronic solvents.  NASA.gov Ozone Hole Watch

13. Solar Energy • The sun delivers heat energy to Earth’s surface. • This is called radiation. • This heat energy is absorbed and also radiated back into space. • The physical characteristics of Earth’s surface affect how much heat energy is absorbed.

14. Solar Energy • Color: • The darker an object, the more heat it absorbs. • Texture: • The rougher an object, the more heat it absorbs. • Therefore, dark and rough objects (like rocks, mountains) absorb the most heat. • Light and smooth objects (like water and snow) do not absorb much at all. Instead, they reflect heat.

15. Specific Heat • The specific heat of a substance is its resistance to heating up or cooling off. • If something’s specific heat is high, it takes a long time to heat up, but will keep the heat for a long time. • If something’s specific heat is low, it will heat up quickly, but also lose the heat quickly. • ESRT ALERT!! – Page 1 contains a chart with the specific heats of some common materials.

16. Water has a very high specific heat – takes a long time to heat water up, but once it’s warm it stays warm for a long time. Metals, like lead and copper have low specific heats – they will heat up very quickly, but cool down very fast too.

17. Energy Transfer • Energy in the atmosphere and at Earth’s surface is transferredin two main ways: • 1. Conduction is the transfer of energy when molecules collide, or actually come in contact with each other. • 2. Convection is the transfer of energy through a substance. It is a circular motion!! • Warm air rises (due to low density), it then expands and cools (density is now high), so the air then sinks back down. This occurs over and over again.

18. Energy Transfer • Think of a pot of boiling water. • Conduction is going on when the flame comes in contact with the pan and heats it up. • Then convectionoccurs within the water itself allowing all the water molecules to heat up and begin to boil.

19. Convection Conduction

20. ESRT ALERT!! - Page 1 – Energy Properties of Water

21. Cause of Weather • Meteorology is the study of atmospheric phenomena. • For example:clouds, raindrops, snowflakes, fog, dust, and rainbows. • The current state of the atmosphere is considered weather. • Weather is a short-term thing and can occur in small areas!!! • On the other hand, climates are long-term and cover entire areas.

22. Causes of Weather • The main cause of weather is due to an imbalance of the sun’s rays hitting the Earth. • The sun’s rays DO NOT hit all spots on the Earth with the same intensity. • Higher latitudes (above Tropics of Cancer and Capricorn) have low intensity sun’s rays. • Lower latitudes (between Tropics of Cancer and Capricorn) have high intensity sun’s rays. • It all has to do with the angle of the sun’s rays!!

23. Causes of Weather • This difference of the sun’s rays causes heat energy to constantly be redistributed, mostly through convection. • Everything then gets brought into balance once the energy gets redistributed. • This entire process creates weather!!

24. Temperature Contrasts Video Clip

25. Temperature • Temperature and heat are NOT the same thing! • Heat is an actual energythat’s transferred. • Temperature is a measurement of that energy. • Let’s remind ourselves of the relationshipbetween temperature and density and temperature and pressure.

26. Temperature • As temperature increases, density decreases and vice-versa. • As temperature increases, atmospheric pressure decreases, and vice-versa. • Keep these in mind in the next few weeks, these are VERY important relationships in weather! • ESRT ALERT!! – Remember on page 13 you will find a temperature conversion scale that will be very useful! Also, there is a pressure conversion scale.

29. Relative Humidity Video Clip

30. Dew Point and Relative Humidity • The dew point is the temperature that air needs to be cooled to in order to be saturated (completely full of water). • When you leave a glass of ice water out on a hot day, the air right around the glass gets cooled to its dew point and forms “dew” or condensation. • The relative humidity is a RATIO of the actual amount of water in the air compared to how much it COULD hold.

31. Dew Point and Relative Humidity • Warm air can hold more moisture than cold air can!! • Therefore, typically we FEEL humidity more on warm days because the air is able to hold more moisture thus it’s filled with more moisture. • On a cold day, it is more likely to snow or rain because the air can’t really hold much moisture so the moisture falls out of the air in the form of precipitation.

32. Dew Point and Relative Humidity • Let’s put the two together! • If dew point is the temperature it needs to be for air to be completely full of water, and relative humidity is the ratio of what’s there compared to what could be there, then what does it mean when the dew point and the actual temperature (dry bulb) are the same number? • It means the air is 100% full of water and that means that the relative humidity is 100%. Weather is very wet – probably raining!

33. Dew Point and Relative Humidity • OK, so what does it mean when the dew point and the actual temperature are just close together but NOT the same number? • It means that the relative humidity is high, but not 100%. Weather is probably not that nice and feels humid. • What about if the dew point and actual temperature are very far apart? • It means the relative humidity that day is very low. Weather is clear and not humid!

34. Dew Point and Relative Humidity • The instrument used to measure dew points and relative humidity is a sling psychrometer.

35. Dew Point and Relative Humidity • Using a sling psychrometer, you obtain the actual temperature outside (dry bulb) and a wet bulb temperature. • With these two numbers and either a dew point or relative humidity chart, you can figure out the dew point or relative humidity. • ESRT ALERT!! – Page 12 contains both a dew point and relative humidity chart. Let’s learn how to use them!

36. Dew Point and Relative Humidity • All you need is the dry bulb number and the wet bulb number. • STEP ONE is to SUBTRACT those 2 numbers!!! • Whatever you get when you subtract those 2 numbers is the number you use at the topof the chart. • Then just use the given dry bulb number for the left side of the chart and where they meet is your answer!! • Let’s try it!

39. Dew Point and Relative Humidity • The dry bulb temperature is 20 ºC and the wet bulb temperature is 16 ºC. What is the dew point? • 20 – 16 = 4 • Use the dew point chart and find 4 at the top and 20 on the left and you end up with 14 ºC as your answer! • Now, use the same dry bulb and wet bulb, but find the relative humidity. • 20 – 16 = 4 • Use the relative humidity chart and find 4 at the top and 20 on the left and you end up with 66% as you answer!

40. Air Pressure Video Clip

41. Wind and Air Pressure • The only reason we have wind is due to airpressure differences on Earth. • When air warms, the pressure drops. • When air cools, the pressure rises. • Air likes to move from high pressure to low pressure. • AIR GO, HIGH LOW • Therefore, we would never have wind if it weren’t for pressure differences.

42. H L H L H L H

43. Wind Video Clip

44. Wind and Air Pressure • Wind is named for the direction its COMINGFROM, NOT the direction its going to. • Therefore, a northeast wind means its coming from the northeast and moving towards the southwest. • Example: Wind speed = 12 mph, Wind direction = SE • This means the wind is moving at 12 mph FROM the southeast.

45. Wind and Air Pressure • When a high pressure system develops, air moves outward from the high pressure area and clockwise. • When a low pressure system develops air moves inward to the low pressure area and counterclockwise.

46. H L

47. Wind and Air Pressure • Air pressure is measured using a barometer. • The units are either millibars (metric) or inches of mercury(English). • Lines that connect equal air pressure on a weather map are called isobars. • The closer the isobars are to each other, the higher the wind speed. • ESRT ALERT!! – Remember, page 13 has a pressure conversion chart which will be helpful.

49. Not so windy!! Windy!!

50. Land and Sea Breezes • Since wind is created when there’s pressure differences, two typical types of breezes occur: • 1. A land breeze • 2. A sea breeze