2 I. Factors of WeatherA. Climate or Weather?1. Climate is….the pattern of weather over an area over manyyears.2. Weather is….the present state of the atmosphere and describesthe current conditions.3.
3 4. Factors that determine the state of the atmosphere.a. Air pressureb. Windc. Temperatured. Amount of moisture in the airB. Humidity1. Water, Nitrogen and Oxygen molecules in theatmosphere.2. Humidity is….the amount of water vapor held in the air.
4 3. At 20 degrees C, the atmosphere can hold 803. At 20 degrees C, the atmosphere can hold15-18g/cubic meter of moisture.4. At 50 degrees C, the atmosphere can hold80g/cubic meter of moisture.5. Warm air can hold more moisture than cold air.6. Damp, sticky summer days are a result of relativehumidity.50
5 C. Relative Humidity1. …is the measure of the amount of water vaporthat air is holding compared to the amount it canhold at a specific temperature.2. If the atmosphere is holding 40g/cubic meter ofof water vapor at 50 degrees C, the relativehumidity would be50%.3. Dew Point is….the temperature at which air is saturated andcondensation takes place.
6 II. Cloud FormationA. Clouds form when….1. Warm air is forced upward, expands, and cools.2. As air cools the amount of water vapor neededfor saturation decreases.3. When relative humidity reaches 100% the air issaturated.4. Water begins to condense around particles in theatmosphere.5. Smaller water droplets become suspended in air.6. When droplets join together clouds form.
7 III. Cloud Classification Clouds are classified by shape.A. Stratus Shape1. Stratus clouds look like smooth even sheets.2. They usually form in the lower troposphere.3. When they are near the ground we call it FOG.B. Cumulus Shape1. Cumulus clouds are puffy and white.2. They form when air currents rise.C. Cirrus Shape1. Cirrus clouds are fibrous and/or curly.2. They indicate fair weather or approaching storms.
8 …and height. A. Cirro describes high elevation clouds. (6000+m) B. Alto describes middle elevation clouds. ( m)C. Strato describes lower clouds. (-2000m)…and rain capacity.A. -Nimbus clouds are associated with precipitation.-Cumulonimbus clouds bring thunderstorms.-Nimbostratus clouds bring long steady rain.B. – Cirrostratus clouds are fine veils made of ice crystals.and may form sun and moon halos.- Altostratus are thick gray cloud sheets that bringcontinuous rain.
10 IV. PRECIPITATIONA. Precipitation is water that falls from the clouds.B. Four types of participation.1. Rain is… drops of water falling when thetemperature is above freezing.2. Snow forms when the air temperature is so coldthat water vapor changes directly to a solid.3. Sleet forms when snow passes through warm air,melts and then refreezes near the ground.4. Hail forms when water drops freeze in layersaround a small nucleus of ice.