Clouds. A simple scientific explanation for the weather-curious. By Kira R. Erickson

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1 Clouds A simple scientific explanation for the weather-curious By Kira R. Erickson

2 Table of Contents INTRO 2 Page 3 How Clouds Are Formed Types of Clouds Clouds and Weather More Information Page 4 Page 10 Page 17 Page 20

3 Introduction What are clouds? A cloud is a visible mass of water droplets or ice crystals floating in the atmosphere above Earth, or another planet. Clouds are made of hundreds of millions of tiny water droplets or ice crystals that stick to dust and salt particles in the atmosphere.. 3

the atmosphere above Earth, or another planet.

4 1 How Clouds Are Formed

5 How Clouds Are Formed The basics Clouds form when water vapor in the air condenses into water droplets or ice crystals, that begin to collide with the dust and salt in the air. When the air temperature drops, the different particles start to stick to each other, causing condensation. As more water droplets or ice crystals join with the dust and air particles, they begin to grow. When the air becomes saturated and cannot hold anymore water particles, clouds form. j = = 5 1

When the air temperature drops, the different particles start to stick to each other, causing condensation.

6 How Clouds Are Formed Ways clouds are formed = = = = = = = = = x Evaporation Occurs when the amount of water in the air increases. Condensation Occurs when the air temperature lowers. 6 1

7 How Clouds Are Formed What causes clouds to form Convectional Lift Orographic Lift Frontal Lift Radiative Cooling When the ground is heated by the sun and causes the air to become warmer and lighter. It then rises, expands, and cools, until it reaches saturation. When air is forced to rise in order to get over an elevated area of physical land. As it rises it cools until it is saturated. When a cooler, more dry air mass comes together with a warmer, more moist air mass. The first mass then rises and cools until it reaches saturation. When the ground and air are no longer being heated by the Sun. The Earth loses energy and the ground and air above it begin to cool. Often produces cumulus clouds. Often produces layered clouds. Creates cumulus clouds and rain. Often causes surface fog. 7 1

When a cooler, more dry air mass comes together with a warmer, more moist air mass. The first mass then rises and cools until it reaches saturation.

8 How Clouds Are Formed How clouds stay afloat!# surface. The water in a typical cloud can weigh up to several million tons. When it weighs more than the warmer air surrounding it, the air currents below and within the cloud keep it afloat above the Earth s 8 1

tons. When it weighs more than the warmer air surrounding it,

9 How Clouds Are Formed Cloud shape The droplets that make up a cloud are constantly forming and re-evaporating, which causes the cloud to continuously morph and evolve. Its shape depends on the strength of the air currents below and within it. Stable air produces homogeneous horizontal clouds. Unstable air creates more vertical clouds. 9 1

Its shape depends on the strength of the air currents below and within it.

10 2 Types of Clouds

11 Types of Clouds e Scientists categorize clouds into different categories based on their heights in the troposphere ,500 ft. High Level Middle Level Low Level 0 ft.

12 Types of Clouds High Level Clouds 16,500-42,500 ft. 42,500 ft. High Level Cirrus Cirrocumulus Cirrostratus Fibrous, threadlike Fleecy Milky, translucent 0 ft. 12 2

13 Types of Clouds Middle Level Clouds 42,500 ft. 6,500 23,000 ft. Altocumulus Altostratus Middle Level Bundles, arranged in banks Dense, opaque layer 0 ft. 13 2

14 Types of Clouds Low Level Clouds 42,500 ft. 0-6,500 ft. Stratocumulus Stratus Nimbostratus Grey rollers or banks Evenly grey, foggy Dark grey rain cloud Low Level 0 ft. 14 2

15 Types of Clouds Other clouds 42,500 ft. 0 42,500 ft. Cumulonimbus Cirrus Kelvin-Helmholtz Mammatus Towering with flat top Wave-like curls Sac-like bulges 0 ft. 15 2

16 Types of Clouds Cloud colors Denser clouds are more reflective, and therefore appear white in color. Clouds can also appear different shades of grey depending on the intensity of the solar radiation throughout their mass of vapor. Thin clouds can take on the color of their environment or background, and clouds illuminated by non-white light such as during sunrise or sunset, may reflect the colors surrounding them. 16 2

17 3 Clouds & Weather

18 Clouds and Weather Rain and snow Rain occurs when the water droplets within a cloud become heavy enough to overcome the lifting effects of the air currents supporting it. Condensation alone can only create water drops big enough for a drizzle. Raindrops are produced when enough cloud droplets combine to create larger, heavier drops. Snow is created high up in the cloud when the temperatures surrounding it are low enough to freeze the water droplets. When the liquid droplets in the cloud coat the snowflakes and then freeze, the flakes become larger ice chunks called hail. 18 & ' % $ 3

Raindrops are produced when enough cloud droplets combine to create larger, heavier drops.

19 Clouds and Weather Thunder and lightning Lightning occurs when the turbulent winds within a cloud lift the water droplets in its lower areas up, causing them to strip the ice and hail that are being pushed downward by downdrafts of their electrons. ( The result is a cloud with a negatively charged bottom, and positively charged top. The electrical fields become increasingly strong until the charge overpowers the atmosphere s properties, and lightning strikes. Thunder is created when the lightning heats the air around it to temperatures of thousands of degrees in a fraction of a second. The air expands explosively, sending out a shockwave. This creates the crack sound, followed by the rumbles of the surrounding air vibrating. 19 3

$Thunder is created when the lightning heats the air around it to temperatures of thousands of degrees in a fraction of a second. The air expands explosively, sending out a shockwave.$

20 4 More Information

21 More Information Cloud. (2014, Aug 5). In Encyclopædia Britannica online. Retrieved from K3JAE Weather Station. (n.d.) Clouds Explained. Retrieved from Met Office. (2013, Oct 28). What are clouds and how do they form. Retrieved from learning/clouds/what-are-clouds Passport to Knowledge. (n.d.). Precipitation. Retrieved from Pidwirny, M. (2006). "Cloud Formation Processes". Fundamentals of Physical Geography, 2nd Edition

22 Contact information thank you For more information, contact Kira Erickson at

If wispy, no significant icing or turbulence. If dense or in bands turbulence is likely. Nil icing risk. Cirrocumulus (CC)

If wispy, no significant icing or turbulence. If dense or in bands turbulence is likely. Nil icing risk. Cirrocumulus (CC) Cirrus (CI) Detached clouds in the form of delicate white filaments or white patches or narrow bands. These clouds have a fibrous or hair like appearance, or a silky sheen or both. with frontal lifting