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Blowin' in the Wind, Issue #016 Weather creation: cloud lesson plans - March 1, 2005
February 28, 2005
Howdy,

# The quick run down - cloud lesson plans.

Have you wondered how we get clouds? The cloud lesson plans outlined below lead you to a series of recent articles to explain how clouds form.

1) Patterns of instability cause air mixing, convection currents and maybe severe storms. We shall explore the mechanics of cloud creation, particularly the tall or puffy type. And see how convection works.

How is the upper atmosphere structured?

The temperature usually falls as you go high into the air. How much? Is it always the same? How do we evaluate it? We always care if ascending air gets too warm or cold, because that will determine what happens afterwards.

In other words, vertical air motion is very important.

This new page http://www.stuffintheair.com/weather-convection-currents.html tells you all about these introductory cloud facts.

# Variety in clouds

2) Unique air motions result in different types of clouds. Air moving up and down gives the clouds their shapes.

Mathematical parameters used to describe sky conditions and predict movement include temperature and dew point. For those who do not like heavy calculations, such as some meteorologists, we use graphs to figure things out.

Believe me, these things really simplify the computations for you.

A few rules of thumb can get you a general idea of what cloud types to expect at certain times. And you can understand rain and fog a little better.

We concern ourselves with air stability, which supports and controls mixing, updrafts and downdrafts. This is how you get clouds.

# What about water vapour?

3) Humidity is the quantity of water in the air.

We get a little more technical here, defining concepts such as lifting condensation level and level of free convection. These things depend on moisture content as much as they do on temperatures.

In a sense, the air above turns upside down and causes turbulence. And if the temperature near the ground gets high enough, deep convection begins. And so can trouble.

# A display of convection

4) You can use thermodynamic charts to see the basic ingredients for thunderstorms. There are lots of curves, points and areas to look at, and they all help you assess the storm potential.

Some clouds suck in air from the ground, but not most high clouds.

See what I mean at

http://www.stuffintheair.com/thunderstorm-cumulonimbus-clouds.html.

5) Instability is the name of the game. Varying mechanisms cause the air to become unbalanced. Where warmer or moist air lies near the ground or below cold dry air. This is a general recipe for storm formation.

Maybe the sunshine makes it too warm below, maybe cold air moves over a warm lake. Maybe air even goes uphill and gives you unexpected results. More cloud lesson plans are listed on this web page: http://www.stuffintheair.com/causes-of-lightning-thunder.html

# So what gives us good weather?

6) This last section deals with stable atmosphere. Here you normally see light winds and sunshine.

What is an inversion? That is where the air is warmer, higher up. It happens occasionally, and usually leads to more pleasant weather.

But it can give us problems too, such as pollution trapping near the ground, fog, drought, and even unseasonal frost.

Get the full story at http://www.stuffintheair.com/weather-inversions.html.

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