Chapter 11 section 3 vocabulary

Condensation nuclei Small particles in the atmosphere around which cloud droplets can form.

Orographic lifting When wind encounters a mountain and the moving air has no where to go but up—this warmer moist air forms clouds when it hits the colder air above.

stability The ability of an air mass to resist rising. This occurs when the air mass is cooling. (if it is warming it wants to rise)

Latent heat Energy stored in water (energy is transferred between water and the atmosphere)

Coalescence When cloud droplets collide and make larger droplets

precipitation When water (liquid or solid) falls to earth

Water cycle Constant movement of water between the atmosphere and Earth’s surface

Evaporation The process of water changing from a liquid to a gas

Types of clouds Cirro = high Alto = middle Strato = low

Types of clouds Cirrus = hair Cumulus = pile or heap Stratus = layer Nimbus = cloud (think rain)

Clouds are classified by what vertical level their bases (or bottoms) form at: Low Clouds: Middle Clouds: High Clouds:

Low Clouds: Low clouds can be on the ground (fog) to ~6,000’ above the surface. 6,000 ft above ground Five low cloud types: Cumulus Stratus and Fog Stratocumulus Nimbostratus Cumulonimbus Lyndon State Green Mountains

Cumulus: Heaped or lumpy looking, most commonly portrayed type in art, film Stratus: Layered or flat looking and grayish Stratus

Stratocumulus: looks both lumpy and layered, flatter than cumulus but more lumpy than stratus Fog: when a stratus cloud touches the ground Fog

Nimbostratus: a stratus cloud that's precipitating – rain and/or snow is falling from the cloud and reaching the ground Cumulonimbus: a cumulus cloud that has precipitation falling from it and reaching the ground Cumulonimbus *Nimbus = precipitating

Middle Clouds: Middle clouds can extend from ~6,000’ to ~20,000’ above the surface. ~20,000 ft above ground Two basic middle cloud types “Alto” prefix: Altocumulus Altostratus 6,000 ft above ground Green Mountains Lyndon State

Altocumulus: look like cotton balls, about the size of your fist or smaller if you extend your arm and look towards them Altostratus: layered and flat, but higher than stratus Altostratus

High Clouds: High clouds can extend from ~20,000’ to 40,000’ above the surface. ~40,000 ft above ground Three basic high cloud types “cirro” prefix: Cirrus Cirrostratus Cirrocumulus ~20,000 ft above ground 6,000 ft above ground Lyndon State

Cirrus: appear wispy in pieces or small patches, not organized in sheets Cirrostratus: wispy - especially on the edges, flat and fairly white, organized in sheets or layers Cirrostratus

Cirrocumulus: fairly rare, look like small cotton balls, about the size of your pinky when you extend your arm and look at the cloud elements. Cirrocumulus

Special Clouds Contrail: short for “condensation trail” – forms when water from air plane exhaust forms clouds behind the plane Contrail Lenticular: type of mid-level cloud Produced by airflow over terrain, frequently mistaken for UFOs Lenticular

Lenticulars over the Salt Lake Valley

Cloud Classification

How do clouds form? Clouds for when warm, moist air rises, expands and cools in a convection current. As the air reaches its dew point, the water vapor in the air condenses around the condensation nuclei

What are Condensation Nuclei ? Small particles in the atmosphere around which cloud droplets can form Ex. Salt, dust, pollen, bacteria, ash

How do clouds form? Cont. Clouds for when warm, moist air rises, expands and cools in a convection current. As the air reaches its dew point, the water vapor in the air condenses around the condensation nuclei. When millions of these droplets collide – a cloud forms.

Collision of AIR MASSES= CLOUDS As warm air moves into the area, it will be forced to rise over more-dense cold air. As the warm air cools, the water vapor in it condenses and forms a cloud.

How are clouds formed by Orographic Lifting? Clouds can also form when wind encounters a mountain and the air has no place to go but up. The effect is the same as with any rising air- it expands and cools.

Topic 7 - Weather

Weather Definition Weather – state or condition of the variables of the atmosphere at a given time Weather variables – temperature, air pressure, wind, moisture, cloud cover, precipitation, storms Weather occurs in the troposphere (lower layer of the atmosphere) Heat energy (insolation) is what drives weather

Temperature Reminder: use page 13 on ref. table to convert temperatures Three Scales: Fahrenheit, Celsius, Kelvin Isotherms – lines that connect equal lines of temperature

Heating the Atmosphere More insolation = higher temperatures Conduction moves heat – Earth’s surface to the atmosphere Absorption of insolation by gases and aerosols Absorption of infrared radiation given off by Earth’s surface Condensation and (sublimation) gives off stored heat Coriolis Effect – due to rotation and winds friction between air and Earth’s surface

Another Important Heat Transfer Convection – due to differences in density Convection Currents – air moving in circular patterns

Expansion and compression When a gas expands its temperature decreases When a gas compresses its temperature increases Air rises expands and cools Air sinks compresses and warms