Moisture, Clouds, and Precipitation

This set of flashcards covers key terms and concepts related to moisture, clouds, and precipitation, focusing on definitions and processes important for understanding atmospheric science.

Calories

A unit of energy used to measure the heat required to raise the temperature of one gram of water by one degree Celsius.

Latent Heat

The energy absorbed or released during a phase change of water without changing temperature.

Evaporation

The process by which liquid water changes into water vapor, absorbing latent heat.

Condensation

The process by which water vapor changes into liquid water, releasing latent heat.

Melting

The process when solid ice absorbs heat energy and changes into liquid water.

Freezing

The process where liquid water releases heat energy and changes into solid ice.

Sublimation

The direct transition from solid ice to water vapor without passing through the liquid phase.

Deposition

The process where water vapor turns directly into ice, releasing latent heat.

Relative Humidity

The ratio of actual water vapor content of the air to the maximum it could hold at a given temperature.

Dew Point Temperature

The temperature at which air must be cooled to reach saturation and condensation begins.

Adiabatic Cooling

Cooling that occurs when air rises and expands due to lower pressure.

Adiabatic Heating

Heating that occurs when air descends and compresses due to increasing pressure.

Orographic Lifting

When air is forced to rise over a mountain, cooling adiabatically and often producing clouds.

Frontal Wedging

Occurs when warm air is forced to rise over cooler air along a weather front.

Convergence

When air flows towards a central area from different directions, forcing it to rise.

Localized Convective Heating

When unequal surface heating creates pockets of warm air that rise.

Stable Atmosphere

An atmosphere that resists vertical motion leading to calm weather.

Atmospheric Instability

When rising air parcels remain warmer than surrounding air, encouraging ascent.

Condensation Nuclei

Tiny particles on which water vapor condenses to form cloud droplets.

Cumulonimbus

A towering, dense cloud associated with thunderstorms and heavy precipitation.

Bergeron Process

Explains precipitation formation in cold clouds through ice crystal growth.

Collision-Coalescence Process

Describes how larger cloud droplets grow by colliding and merging with smaller droplets.

Rain

Liquid water droplets that fall from clouds when sufficiently large.

Drizzle

Light precipitation composed of very small water droplets.

Snow

Forms when ice crystals in clouds combine and fall to the ground.

Sleet

Small pellets of ice formed when raindrops freeze before reaching the ground.

Glaze

Freezing rain that forms a smooth layer of ice upon contact with cold surfaces.

Hail

Forms in strong thunderstorms when updrafts carry raindrops into freezing regions.

Rime

A deposit of ice crystals formed by the rapid freezing of supercooled water droplets.

Humidity Control Factors

Factors such as temperature, proximity to water, vegetation, and air movement that affect humidity.

Humidity Measurement

Determined using hygrometers or psychrometers to compare air temperature and dew point.

Dew Point Effects

At the dew point, air becomes saturated and condensation begins.

Adiabatic Temperature Changes

Observed when rising air expands and cools or sinking air compresses and warms.

Wet vs. Dry Adiabatic Rates

Dry rate ~10°C/1000m; Wet rate ~5-6°C/1000m due to heat release during condensation.

Vertical Air Lifting Methods

Includes orographic lifting, frontal wedging, convergence, and localized convective heating.

Stable vs. Unstable Atmosphere

Stable leads to calm weather; unstable promotes rising air and storm development.

Cloud Formation Mechanisms

Air cooling to its dew point and condensation on nuclei via lifting mechanisms.

Types of Precipitation

Includes rain, snow, sleet, hail, glaze, and drizzle based on temperature and cloud processes.

Precipitation Measurement

Measured using rain gauges, tipping-bucket gauges, or radar systems.

Weather Modification Techniques

Methods like cloud seeding, hail suppression, and fog dispersal to influence precipitation.