Science 10: Mr. Jean January 12 th, 2012

The plan: Video clip of the day Atmospheric Layers Aurora Clouds BBC – Deep Freeze

Atmospheric Layers 4 layers are defined by constant trends in average air temperature (which changes with pressure and radiation), where the outer exosphere is not shown. 1.Troposphere 2.Stratosphere 3.Mesosphere 4.Thermosphere

Atmospheric Layers Figure 1.7 Troposphere – Temp decrease w/ height Most of our weather occurs in this layer Varies in height around the globe, but Averages about 11 km in height.

Atmospheric Layers Figure 1.7 Stratosphere Temperature increases in stratosphere. Ozone plays a major part in heating the air at this altitude

Atmospheric Layers Figure 1.7 Mesosphere Middle atmosphere – Air thin, pressure low, Air quite Cold -90°C (- 130°F) near the top of mesosphere

Atmospheric Layers Figure 1.7 Thermosphere “Hot layer” – oxygen molecules absorb energy from solar Rays warming the air. Very few atoms and molecules in this Region.

The Earth has magnetic field that saves us from being fried by cosmic radiation. When cosmic particles get trapped in this magnetic field they get “excited” with energy and give off light.

Aurora (Northern Lights)

A cloud is a visible aggregate of tiny water droplets and/or ice crystals suspended in the atmosphere They can exist in a variety of shapes and sizes. Some clouds are accompanied by precipitation; rain, snow, hail, sleet, even freezing rain. CLOUDS:

Condensation Nuclei Tiny particles (dust, salt) which stimulate droplet formation

Water is known to exist in three different states; as a solid, liquid or gas. Clouds, snow, and rain are all made of up of some form of water. A cloud is comprised of tiny water droplets and/or ice crystals A snowflake is an aggregate of many ice crystals Rain is just liquid water.

Water existing as a gas is called water vapor. When referring to the amount of moisture in the air, we are actually referring to the amount of water vapor. If the air is described as "moist", that means the air contains large amounts of water vapor. Common sources of moisture are the Maritime Air masses.

A cloud naming system was invented in 1802 by Luke Howard. Clouds are classified into a system that uses Latin words to describe the appearance of clouds as seen by an observer on the ground. The table below summarizes the four principal components of this classification system Latin RootTranslationExample cumulus stratus cirrus nimbus heap layer curl of hair rain fair weather cumulus altostratus cirrus cumulonimbus

Classifying Clouds Clouds are classified according to their form and altitude.  The three main forms: stratus clouds, cumulus clouds and cirrus clouds.  The three altitude groups: low clouds (up to 2000m) middle clouds (2000 – 6000m) high clouds (above 6000m)

Stratus Clouds - flattened, layered shape - cover large areas of sky - usually form when a warm air mass overruns a cold air mass - indicate stable conditions Cumulus Clouds - puffy, “heaped” shape - created by convective or frontal cloud formation - usually indicate unstable weather

Cirrus Clouds - thin, wispy clouds - the highest clouds in the sky - created by wind blown ice crystals - usually indicate fair weather One more cloud sub-classification is the word nimbus indicating a rain carrying cloud

Alto = mid-level cloud

High-Level Clouds Cirrus - high-level clouds form above (6,000 meters) and since the temperatures are so cold at such high elevations, these clouds are primarily composed of ice crystals. High-level clouds are typically thin and white in appearance. They move across the sky on bright sunny days. Cirrus clouds mean warm air is on the way.

Cirrus - High-level clouds

Mid-Level Clouds The bases of mid-level clouds typically appear between 2,000 to 6,000 metres. Alto- clouds, because of their lower altitudes, are composed primarily of water droplets, they can also be composed of ice crystals when cold enough. Altocumulus Clouds parallel bands or rounded masses

Low-level Clouds Low clouds are mostly composed of water droplets since their bases generally lie below 2,000 meters. When cold enough, these clouds may also contain ice particles and snow. Nearly all low clouds are some form of stratus cloud. Nimbostratus Clouds dark, low-level clouds with precipitation

Stratus Clouds

Fair Weather Cumulus Clouds puffy cotton balls floating in the sky Fair weather cumulus have the appearance of floating cotton with flat bases have a lifetime of 5-40 minutes. The cloud tops designates the limit of the rising air. Given suitable conditions, however, harmless fair weather cumulus can develop into cumulonimbus clouds associated with thunderstorms.

Cumulus Clouds

Classification of Clouds Sheet Label the diagram with the correct name at the appropriate altitude.

Stratus

tennialofflight.gov/2003FF/clues/clipart/stratus.jpg

Stratus

Nimbostratus

Cumulus

Stratocumulus

Altocumulus Altostratus

Cumulonimbus Base of cloud

Cumulonimbus

Cirrocumulus Cirrostratus

Cirrocumulus

Cirrus

Cirrus:

Nimbus