Mid-Level Clouds

Mid-level clouds(Family B) include Altostratus and Altocumulus cloud types.
Altostratus clouds form when a rising air mass condenses when in contact with a weather front.
They are often thin and allow sunlight through.They form in a layer.
Altocumulus clouds form the same way as Altostratus do but in a different appearance.
They are thicker in altitude and do not allow light through.Both cloud types can cover thousands of square kilometres.
Altostratus

(eo.edcar.edu)

Altocumulus

(wikipedia)

High Level Clouds

High level clouds ( family A) usually form at the edge of a warm front.
They indicated fair weather.They are made of super cooled or
frozen water droplets which have been deposited at high altitudes.
They also indicate that the weather will change within 24 hours.
They have a temperature of -20⁰C  to -30⁰C.

Cirrus

(Wikipedia)
Cirrocumulus

(Wikipedia)

Cirrostratus

(Windows to the Universe, Lisa Gardiner)

Different Types of Clouds

Clouds are classified by their altitude, shape and name.
As seen in the video below there are three general categories of clouds;

1. High level clouds - 6'000m - 12'000m (20'000ft - 40'000ft)
                              - these include: Cirrus, Cirrostratus, Cirrocumulus

2. Mid-level clouds - 2'000m - 6'000m (6'500ft - 20'000ft)
                             - these include: Altostratus, Altocumulus

3. Low level clouds - 0m - 2'000m (0ft - 6'500ft)
                              - these include: Stratus, Nimbostratus, Stratocumulus

How Clouds Form

When the sun heats the surface of the earth, surface water such as oceans, lakes and rivers evaporate water into the atmosphere. This happens because the suns heat also warms the air above the earths surface.This warm air rises and carries the evaporated water. When the warm air ascends it becomes cooler and is not able to hold as much water vapour. The water vapour (gas) condenses into water droplets (liquid). The water droplets attach to pieces of atmospheric dust (condensation nuclei) and clump together to form clouds. Clouds reflect the suns light so they appear white. If a cloud becomes dense it will appear more of a grey colour because it blocks the suns light . Clouds can form at different heights and sizes due to air pressure, air temperature, wind conditions and weather systems. When a cloud reaches its saturation point it rains(precipitation).The cloud has reached 100% relevant humidity.This completes the water cycle.

Introduction

This blog is about the geography of clouds.
Over the next few weeks I will write about:

• How clouds form
• Different types of clouds
• The journey of a cloud
• Cloud spotting and appreciation
• Clouds on solar system planets