1kspieker

Miss JosephPeriod 1

By: Katelyn Spieker

Clouds and Precipitation

When air can’t expand, it cools. When it gets compressed, it warms.Temperature changes that occur when heat isn’t added or subtracted are called adiabic temperature changes.Although the air will continue to cool after condensation starts, the latenet heat that gets released works against the adiabatic cooling process.

Adiabatic Temperature Changes and Expansion and Cooling

http://iopscience.iop.org/1367-2630/10/6/065001/fulltext/

When elevated terrains, like mountains, take position as barrier to air flow, orographic lifting of air occurs.

As air makes its way up a mountain slope, adiabatic cooling often generates precipitation and clouds.

Many of the places most rainy on Earth are located on these windward mountain slopes.

Orographic Liftinghttp://ocw.usu.edu/Forest__Range__and_Wildlife_Sciences/Wildland_Fire_Management_and_Planning/Unit_7__Atmospheric_Stability_and_Instability_3.html

In central North America, heaps of cold air and warm air collide. This produces a front.

The cooler, denser air acts as a barrier over the warmer less dense air as it rises.

Weather-producing fronts are related to specific storm systems called middle-latitude cyclones.

Frontal Wedging

http://www.geo.hunter.cuny.edu/~tbw/wc.notes/4.moisture.atm.stability/frontal_wedging.htm

When air in the lower atmosphere flows together, the result is lifting (convergence)

If air flows in from more than one direction, it must go somewhere.

Because it cannot go down, it goes up, leading to adiabatic cooling and a possibility of clouds forming.

Convergence

http://en.wikipedia.org/wiki/File:Oceanic-oceanic_convergence_Fig21oceanocean.gif

On warm summer days, uneven heating of the Earth’s surface can cause pockets of air to be warmed more than the air that is surrounding it.

The method that produces increasing thermals is localized convection lifting.

When warm air parcels of air ascend above the condensation level, clouds form.

Localized Convective Lifting

http://rst.gsfc.nasa.gov/Sect14/Sect14_1c.html

If a quantity of air was required to rise, its temperature would drop because of expansion.

If this volume of air was cooler than the surrounding environment, it would be denser, and if permitted to do so, it would drop to its original location.

STABILITY (DENSITY DIFFERENCES & STABILITY AND DAILY WEATHER)

http://deved.meted.ucar.edu/marine/mbl/print.htm

Air must be saturated for condensation to occur.

Saturation occurs most commonly when the air is cooled to its dew point. It occurs less often when water vapor is added to the air.

Condensation

http://keep3.sjfc.edu/students/kes00898/e-port/condensation%20page%20for%20unit.html

Clouds are classified based on their height and form.

Cirrus= a curl of hair (clouds are high, white and thin)

Cumulus= a pile (clouds consist of rounded individual could masses)

TYPES OF CLOUDS

http://eo.ucar.edu/webweather/cloud3.html

There are 3 types of high clouds- Cirrus, Cirrostratus and Cirrocumulus.

All high clouds are thin and white. They often are made of ice crystals.

This is because of the low temperatures and small amounts of water vapor that are at high altitudes.

High Clouds

http://mynasadata.larc.nasa.gov/glossary.php?&letter=H

Clouds about 2,000 to 6,000 meters high have the prefix alto as part of their name.

Altocumulus clouds are made up of rounded masses that vary from cirrocumulus clouds in that altocumulus clouds are larger and denser.

Altostratus clouds create a uniform white to grayish sheet that covers the sky with the sun or moon, looking like a bright spot.

Middle Clouds

https://www.meted.ucar.edu/sign_in.php?go_back_to=http%253A%252F%252Fwww.meted.ucar.edu%252Ffire%252Fs290%252Funit6%252Fprint_2.htm##

There are 3 members in this family of clouds; Stratus, Stratocumulus and Nimbostratus.

When stratus clouds develop a scalloped bottom, it appears as long parallel rolls or broken rounded patches. Those clouds become Stratocumulus clouds.

Nimbostratus clouds get their name from the Latin word nimbus, which means “rainy cloud” and stratus which means “to cover with a layer”

Low Cloudshttp://www.free-online-private-pilot-ground-school.com/Aviation-Weather-Principles.html

There are a few clouds that don’t fit into any one of the 3 height categories.

These clouds are in the low height range but often extend upward into the middle or high altitudes.

Once upward movement is triggered, acceleration is powerful and clouds that have a high vertical range form.

Clouds of Vertical Development

http://www.astrobio.net/pressrelease/3936/the-secrets-of-the-rain

As the air cools, it becomes denser and drains into low areas such as river valleys where thick fog accumulations can take place.

When cool air moves over warm water, enough moisture may evaporate from the water surface to create saturation.

As water vapor that is rising meets the cold air, it immediately condenses and rises with the air that is being warmed from below.

FOG (BY COOLING AND BY EVAPORATION)

http://www.williamsclass.com/EighthScienceWork/Atmosphere/AtmosphereFog.htm

The Bergeron process relies on 2 physical processes: super saturation and super cooling.

Water in the liquid state below 0 degrees Celsius is said to be “super cooled”.

When air is saturated (100% relative humidity) with the exception to water, it is “super saturated” (with the respect to ice: greater than 100% humidity)

Cold Cloud Precipitation (Bergeron process)

http://www.kidsgeo.com/geography-for-kids/0112-bergeron-process.php

In warms clouds, the mechanism that forms raindrops is the collision-coalescence process.

As these large droplets move through the cloud, they collide and join together with smaller, slower droplets.

Warm Cloud Precipitation (collision-coalescence process)

http://www.atmo.arizona.edu/students/courselinks/spring07/nats101s2/lecture_notes/mar30.html

In meteorology, the term rain means drops of water that fall from a cloud and have a diameter of at least 0.5mm.

When the surface temperature is above 4 degrees Celsius, snowflakes usually melt and continue their decent as rain before they reach the ground.

When temperatures are very low (when the moisture content of air is small) light, fluffy snow made up of individual six-sided ice crystals form.

Rain and Snow

http://www.shutterstock.com/pic-65745589/stock-photo-heavy-cloud-with-rain-and-snow-hi-res-d-rendered-icon-with-clipping-paths.html

Sleet is the fall of small particles of clear to translucent ice.

Hair is produced in cumulonimbus clouds.

If the ice pellets come across a strong updraft, they may be carried upward and begin the downward journey again.

Sleet, Glaze and Hail

http://kvgktrailblazers.weebly.com/forms-of-precipitation.html