All images courtesy of the National Weather Service unless otherwise indicated.

Chapter 18: Water in the Atmosphere 18.2 Clouds High: Above 7000 meters Cirrus Cirrostratus Cirrocumulus

Cirrus

Cirrostratus

Cirrocumulus

Chapter 18: Water in the Atmosphere 18.2 Clouds Middle: About 2000 to 7000 meters Altostratus Altocumulus

Stratus

Altostratus

Chapter 18: Water in the Atmosphere 18.2 Clouds Low: Below about 2000 meters Stratus Nimbostratus Stratocumulus Cumulus

Stratus

Nimbostratus

Stratocumulus

Cumulus

Cumulonimbus

(photo taken from a passenger jet) Cumulonimbus (photo taken from a passenger jet)

Thunderstorm Animation Cloud Animation http://www.clouds365.com/video/ Thunderstorm Animation http://vimeo.com/48731737 http://vimeo.com/15084868

Cloud Formation & Satellite Imagery

Cumulus Cloud Formation Condensation Level: the height at which clouds form Dependent on a constant supply of warm, moist air Also dependent on temperature and dew point temperature

Condensation Level

Cumulus Cloud Formation Dry-adiabatic lapse rate: the rate at which unsaturated air cools with height (~10°C/km) Moist-adiabatic lapse rate: the rate at which saturated air cools with height (~5 to 9°C/km)

Moist-adiabatic Lapse Rate Dry-adiabatic Lapse Rate

Cumulus Cloud Formation Why is the moist rate less than the dry rate? Condensation releases heat Warms the air around it, increasing the temperature This is due to the high heat capacity of water

Cumulonimbus Clouds Form the same way as cumulus clouds, except density differences between the surface air and the air aloft is greater (unstable) Causes the air inside to rise more quickly and achieve greater heights

Cumulonimbus Cloud Diagram http://www.uwsp.edu/geo/faculty/ritter/images/atmosphere/severe%20weather/mature_stage_NOAA_nssl1012.jpg

Layer Clouds Form in stable air; the density difference between the surface air and the air aloft is small Causes the air inside to spread out horizontally rather than vertically like cumulus clouds

Layer Clouds Can form in 2 ways: Air can be forced slowly upward to its condensation level The layer of air can cool to its dew point by radiating heat or mixing with cooler air

Satellite Imagery

GOES Weather Satellites There are a few satellites orbiting Earth gathering many types of weather data, including “pictures” of clouds Satellites are centered over the equator, over 22,000 miles up Geosynchronous: orbits Earth at same rate of Earth’s rotation

Satellite Imagery There are 3 main types of images: Visible: visible light from the sun is reflected to the satellite Infrared: infrared light (heat) is sensed Water vapor: detects moisture in mid/upper troposphere

Compare 3 Images http://www.srh.noaa.gov/jetstream/remote/goes.htm http://www.weather.gov