Adiabatic Temperature Changesand Expansion and Cooling Temperature changes, even without adding or subtracting heat is called adiabatic temperature changes. When air expands, it cools and when compressed, it warms. Moving upward the air expands and cools due to passing regions of low pressure. Cooling generates clouds and precipitation kidsgeo.com Unsaturated air cools at 10 degrees Celsius every 1000 meters upward.
Orographic Lifting Elevated land, like mountains, that blocks air flow proves orographic lifting is occuring. More rain occurs on the windward side. An example is the Great Basin Desert is cut off by the Sierra Nevada Mountains. examiner.com
Frontal Wedging Warm air colliding with cool air produces a front. Cool dense air is a barrier to the warm air that rises. geo.hunter.cuny.edu
Convergence When air in the lower atmosphere flows together, lifting occurs. This is called convergence. Air flows from more then one direction and when it can’t go down, it goes up. Convergence causes clouds and precipitation. ww2010.atmos.uiuc.edu
Localized Collective Lifting Unequal heating of Earth’s surface may cause pockets of air to be warmer then the surrounding air. Rising parcels of warm air are called thermals. Process that makes parcels is localized collective lifting. Parcels that rise above condensation richhoffmanclass.com level results in the formation of clouds and possible rain showers.
Stability Stability is when the air is cooler then its surroundings. Air is dense and sinks to original position resisting vertical movement.Difference: presstv.ir Stable air remains in the same position while unstable air rises.Stability and Daily Weather: Stable air is forced upward by other processes Clouds are widespread and have little vertical thickness. Lifting of unstable air results in thunder storms and possible tornados. On overcast, dreary days stable air has been forced up Puffy clouds means unstable air rose.
Condensation Happens when water vapor in the air changes to a liquid. Forms dew, fog, or clouds. Must be at a surface for the water vapor to condense on. Clouds occur when water vapor uses weatherquestions.com condensation nuclei as its surface.
Types of Clouds Clouds are classified based on form and height.Cirrus: High, white, and thin.Cumulus: Rounded and individuals. eo.ucar.eduStratus: Sheets cover most or all of the sky. There are no individual clouds. Three levels of clouds: high, middle, and low.
High Clouds Bases are above 6000 meters. Cirrocumulus: fluffy. Cirrostratus : eo.ucar.edu flat layer, thin, white, and made up of ice crystals. Due to low temperature (the higher, the cooler) and the small amount of water vapor there is no rain. High clouds show warning of stormy weather
Middle Clouds Bases are 2000-6000 meters high. Altocumulous: rounded, large, and dense. Altostratus: White or gray sheet that covers the sky. Produce light snow drizzle. bigbranch.net
Low Clouds Bases are 2000 meters or below. Stratus: Foggy layer that covers the sky Produce occasional precipitation eo.ucar.edu Stratocumulous: appear in patches Develop at the bottom of a stratus cloud. Nimbostratus: They are the most common precipitation makers They form during stable conditions It’s a rainy cloud that covers the sky.
Clouds of Vertical Development Some clouds don’t fit into the three categories. Their base is at a low range but extend upward into the middle and higher range. Due to unstable air. One cloud is called cumulonimbus which causes rain and thunderstorms. Cumulus clouds fit in this category. bigbranch.net
brainharmonycenter.comFogFog: Clouds with bases near the ground. Happens due to radiation cooling or movement or air over a cool surface.Cooling: Cools rapidly by radiation on cool, clear nights. A thin layer of air near the ground is cooled below dewpoint. Air cools and becomes dense, draining into low areas.Evaporation: There is a steaming appearance. When cool air is over warm water there may be enough moisture to evaporate and produce saturation Increase in water vapor.
Cold Cloud Precipitation Bergeron process relies on two processes: supercooling and supersaturation. Water below 0 degrees Celcuis is supercooled. Ice crystals grow as cloud droplets do, when they are big enough they will fall. When the surface temperature is rst.gsfc.nasa.gov above 4 degrees Celcuis, snowflakes will melt before reaching the ground.
Warm Cloud Precipitation In warm clouds, the formation of raindrops is called collision-coalescence process. Water absorbing particles remove water vapor from air at relative humiditys less than 100% forming large drops that collide and join with smaller, slower droplets apollo.lsc.vsc.edu
Rain and Snow Rain means drops of water that fall from a cloud. Small drops are called a drizzle. Snow turns to rain before even hitting the ground when the surface roymiller.hubpages.com temperature is above 4 degrees celcuis. At low temperatures, light, fluffy snow made of ice crystals form. At temperatures warmer than 5 degrees celcuis,I ice crystals are larger clumps. itunes.apple.com
wunderground.comSleet, Glaze, and HailSleet: The fall of small particles of clear ice. Forms when a layer of air with temperatures above freezing over lay a subfreezing layer near the ground. sercc.comGlaze: Freezing rain Happens when raindrops become supercooled. Turn solid when impacting objects.Hail: Produces in cumulonimbus clouds. rufinope.comlu.com Small ice pelets grow by collection of supercooeld water droplets as they fall through clouds.
Bri’s Presentation on Clouds and Precipitation! The End!