2 What are Clouds? Clouds are made of water. They are either made up of small liquid water drops or tiny ice crystals.Meteorologists are scientists who study the weather, including clouds.
3 A few other termsRelative Humidity – is the % of water vapor in the air compared to how much it can hold at that temperatureDew Point - is the temperaturewhen water vapor turns to liquidEvaporation – the change fromliquid to gasCondensation – the change fromgas to liquid
4 Condensation Nucleii Tiny particle upon which condensation can occur. Required for clouds to form.Examples: dust, chemicals, and bacteriaBathroom MirrorCondensation Nucleii
5 Clouds and Levels Low-level clouds are found below 2 km Mid-level clouds are situated from 2 to 6 km high & have the prefix ALTOHigh-level clouds are above 6 km in altitude
6 How do Clouds Form?Basically clouds form as warm air at the surface of the earth rises.As the parcel of air rises into the atmosphere, it cools.Cool air cannot hold as much water vapor as warm air, so at a certain cool temperature, the water vapor condenses out of the air and forms clouds.
7 There are several ways that a parcel air can be forced to rise: 1. Surface Heating – the sun warms the air and then the warm air rises because it is less dense.Also called Convective Lifting
8 2. Mountains – air is forced upwards as it runs into the higher terrain. Also called Orographic Lifting
9 3. Fronts - When an air mass of one temperature meets another, the warmer air mass will rise over the cooler air mass. (Frontal Lifting)4. Air Pressure - When an air mass moves into a lower pressure area, the air will force the air that was there before, upwards. (Convergence Lifting)
10 Name the process responsible for forming clouds in each of the diagrams: Convection Lifting orSurface HeatingFrontal LiftingConS
11 Convergence Lifting/Moving into a Low pressure area Orographic/Mountain Lifting
12 Fun FactsAdvection cooling - When an air mass cools down because the air mass has moved into a cooler area or on top of a cooler surface.Adiabatic cooling - When air rises it cools. Air temperature decreases with increasing elevation. Usually associated with Orographic (mountain) lifting.
13 Cloud Worksheet - notes Fill in the chart on pages 22 to 24 using the next few slides
14 Cumulus Clouds – page 22They have a fluffy, puffy or billowy appearance, much like cotton balls or cauliflower heads, often very white in color.They are made of tiny water droplets that occur in clumps which then rapidly rise when the sun heats themThey are associated with fair weather and blue skiesCumulus clouds are found at all altitudes
16 Stratus Clouds – page 22These are featureless sheet-like clouds, usually grey in colorThey are made from a huge amount of fine water droplets called water vaporThese clouds produce overcast skies, light mist or drizzleThey occupy low altitudes
18 Nimbus Clouds – page 23Can take on many different appearances, often puffy and either white or grey. Often called Storm clouds.Made up of a large amount of large water dropletsCreate heavy rain or snowFound at low levels
22 Cirrus Clouds –page 23Delicate looking, often wispy, curly, feathery, like horsetailsMade up of ice crystalsMay occur when weather is nice, but sign of bad weather to comeThey occur at high altitudes
29 Cloud Formation - summary Warm air rises and coolsThe water vapor in the air condenses to liquid water dropletsTo do so, condensation nucleii are neededParticles of dust, pollen or smoke provide a cool surface upon which the water vapor can condense on
30 Worksheets: Clouds and What they Mean Complete the 4 pages of worksheets pOmit Question 2 on page 25See /pdfs/cl957-cvxak.pdf
36 Page 28process that converts liquid to gas (liquid water to water vapor)temperature where water vapor in the air converts to liquid water drops% of water vapor in the air at a specific temperature and time. It can be increased by heating the air and by increased evaporationtiny water droplets or ice crystals ranging from below 2 kms to over 6kms above the ground.
37 Page 285. Condensation nuclei (dust particles) are needed for the water vapor to condense on and warm air must rise6. Cumulus7. Nimbostratus (or just stratus)8. Cumulonimbus (present during thunderstorms)9. a. Precipitation (rain or snow)b. Middlec. Sheet; Layers10. Rain, snow, sleet, hail or mist
44 Cloud Formation Worksheet p. 46 The warm air is rising, expanding and becoming less dense. As it cools, the moisture in the air condenses upon condensation nucleii, forming cloudsThe warm air is less dense and the cold air is pushing it upThe mountain is causing the air to riseC BA AE BB CAir Mass FalseAB