Climate and Atmospheric Processes: Key Concepts in Meteorology and Hydrology

Specific heat

How hard it is to heat something up; water needs lots of energy to warm.

Latent heat of vaporization

Energy needed to turn liquid water into steam with no temperature change.

Clausius-Clapeyron

Warm air can hold more water; hotter = bigger air "sponge."

Saturation vapor pressure

The maximum water vapor air can hold before it rains.

Net radiation

How much sunlight energy the Earth keeps after subtracting what it sends back.

Hadley Cell

A big air loop where warm air rises at the equator and sinks at 30°.

Lapse rate

The higher you go in the sky, the colder it gets.

Dry adiabatic lapse rate

Unsaturated air cools fast when it rises (10°C per km).

Moist adiabatic lapse rate

Saturated air cools slower because it releases heat from condensation.

Adiabatic process

Air gets colder or warmer just by expanding or squeezing, with no heat added.

Latent heat

Hidden heat used for changing water's form (like liquid to vapor).

Ferrel Cell

Middle-latitude air loop that creates the winds we feel.

Coriolis effect

Air curves as it moves because Earth spins; right turn in the north, left in the south.

Baroclinic process

Storm-making when warm and cold air masses meet.

Barotropic process

Weather that forms when everything is the same temperature.

ITCZ

Belt around the equator where winds meet and make heavy rain.

Rossby waves

Big wiggles in the jet stream that cause hot or cold weather spells.

High pressure

Air sinks, warms, and makes sunny weather.

Low pressure

Air rises, cools, and makes clouds and rain.

Troposphere

Lowest part of the atmosphere where all weather happens.

Condensation

Water vapor cooling and turning into tiny water drops.

Cloud

A group of tiny water drops or ice floating in the air.

Convectional precipitation

Air heated by the sun rises fast and forms thunderstorms.

Convergent precipitation

Two winds crash together and force air upward to make rain.

Large-scale stable condensation

Gentle lifting of air that causes long-lasting steady rain.

Orographic precipitation

Mountains push air up, causing rain on one side.

Virga

Rain that falls but evaporates before it reaches the ground.

Atmospheric River

A long "river" of water vapor in the air that brings lots of rain.

South Pacific Convergence Zone

A diagonal rain band in the South Pacific with warm ocean water.

Monsoon

Seasonal wind change that brings wet summers and dry winters.

C-C scaling

Every 1°C of warming means air can hold about 7% more water.

Held-Soden relationship

Rainfall increases slowly (1-3% per °C), not as fast as moisture.

Wet-get-wetter pattern

Rainy places get even rainier as the world warms.

High-latitude amplification

The poles warm faster than the rest of the Earth.

Plant physiological effect

Plants "sweat" less water when CO₂ is high because they close their pores.

Transmissivity

How much sunlight passes through the air.

Absorptivity

How much sunlight the air or ground absorbs.

Reflectivity

How much sunlight bounces off; shiny things like snow reflect a lot.

Snow Water Equivalent (SWE)

How deep the water would be if you melted all the snow.

Snow density

How packed and heavy the snow is.

Snow metamorphosis

Snow crystals changing shape and becoming denser as time passes.

Snowmelt

Snow turning into water when warmed.

Cryosphere

All frozen parts of Earth: snow, ice, glaciers.

Runoff ratio (R)

How much of a river's water comes from melted snow.

Evapotranspiration (ET)

Water leaving the land through evaporation and plant "breathing."

Evaporation

Water turning into vapor and rising into the air.

Transpiration

Water traveling through plants and leaving through their leaves.

Penman-Monteith equation

Formula that tells how fast water moves into the air from land and plants.

Infiltration

Water soaking down into the soil.

Hydraulic conductivity (K)

How easily water moves through soil.

Saturated hydraulic conductivity

How fast water moves through soil when it is completely full of water.

Field capacity

How much water soil can hold after extra drains away.

Wilting point

Soil is so dry that plants cannot pull water from it anymore.

Darcy's Law

Water in soil moves from wetter areas to drier areas.

Soil water potential

How strongly water is being "pulled" in soil or plants.

Gravitational potential

Water has more energy when it's higher up and flows downward.

Pressure potential

Water pressure pushing or pulling inside plants.

Osmotic potential

Water moves toward places with more salt.

Matric potential

Water sticks to soil particles more when the soil is dry.

Runoff

Water flowing over the land into streams or rivers.

Baseflow

Slow groundwater that feeds rivers even when it's not raining.

Interflow

Water moving sideways through soil into streams.

Watershed

The area where all water drains into the same river or lake.

Water balance

Long-term equation: rain = evaporation + runoff.

Temperature-energy calculation

More energy makes water warmer based on a formula.

Saturation vapor pressure calculation

Use the CC equation to find how much water vapor air can hold.

Snow Water Equivalent calculation

Melted water depth = snow depth × density ratio.

Lapse-rate temperature change

Temperature drops as you go higher using the lapse rate.

Uneven solar radiation

Different parts of Earth get different sunlight, creating winds and climates.

Timing of California snow

Snow gets deepest in Feb-March and melts in April-June.

Global precipitation control

Big systems like the ITCZ, Hadley Cell, monsoons, and storms create rainfall patterns.

Reforestation effect on ET

Trees increase ET and shade the land, lowering net radiation.

Transpiration role globally

Plants send lots of water vapor into the air, helping make rain.