Weather and climate exam two

Stefan-Boltzmann law

As an object gets hotter it emits more energy (to the fourth power)

Wein’s law

The type of radiation matter emits is proportional to the temperature of the object. As temperature goes up, the wavelength it emits decreases!!!

The sun emits

shortwave radiation: mostly visible, also infrared, UV

The earth emits

longwave radiation. Earth emits infrared (absorbs sunlight, warms up, re- emits energy)

Reflection

Radiation is redirected away from object/medium

Transmission

Radiation passes through an object unaltered, makes its way through the atmosphere

Absorption

might find gas it interacts with, increases temperature of molecule, object/medium takes on the energy, causing it to heat up

Emission

Object then re-emits energy

Scattering

Reflection but happens in all directions

Albedo

The reflective quality of a surface. Amount of energy reflected divided by the incoming radiation, the brighter the surface the higher the albedo

Rayleigh scattering

deflection and redirection of insolation by atmospheric gasses; the shorter the wavelength, the greater the scattering, thus skies in the lower atmosphere are blue

Why is the sky blue

rayleigh scattering

Why is the sunset red

Sunlight has to travel through more atmosphere (because not directly overhead) so blue light is scattered out and doesn’t make it into our eyes

Refraction

The process in which the direction of energy propagation is changed because of energy passing through an interface representing a density discontinuity between two media

Index of refraction

however much light is bent, colors are bent more or less ex. angle of purple is steeper than red

Dispersion

Occurs when shorter wavelengths are refracted more than longer wavelength

Rainbows

Water has different density than air so light is bent. Diff colors interact differently with water droplets, light comes in a gets reflected back spread apart in individual colors. reflect at diff angles (only see red at top)

Energy balance/budget

Temperature at any given location and time on earth is dictated by the budget of energy received by the sun vs the amount that is lost to space

Net radiation

The balance of energy in minus energy out

Greenhouse effect

stores energy for a little bit longer, without actually getting hotter. Reason we have life on earth: supports water, plants, animals but doesn’t make it uninhabitable

Greenhouse effect in atmosphere

shortwave radiation freely transmits through the atmosphere, greenhouse gases absorb longwave radiation emitted by the earth, then re-emit some back towards surface, which heats up

Net in the tropics

positive, we gain more radiative energy than we lose at the equator (surplus). More water in atmosphere, more latent heat

Net at the poles

Negative, we lose more radiative energy than we gain at the poles (deficit)

Greenhouse effect measured

33 K (Kelvin)

Time of day most insolation

Incoming solar radiation highest around noon (max energy), max temp around 3-5 (delay)

Time of year most insolation

Highest in june, close to summer solstice, but max temp in between july and august (delayed).

Fahrenheit

0 coldest temperature in a lab, 100 arbitrary temperature of the human body

Celsius

0 freezing point of water, 100 boiling point of water

Kelvin

starts at absolute zero, which is no energy (consistent everywhere). F and C both have negative values, implying negative kinetic energy

Climate normal

moving 30 year window average, current 1997-2026

Latitude and temperature

higher (more poleward) latitudes experience cooler overall temperatures and a larger annual temperature range

Elevation and temperature

temperatures decrease with increasing altitude (environmental lapse rate), same with air density. Daily temperature range increases with increasing altitude

Topography: aspect

South facing slopes receive insolation at a more direct angle in the northern hemisphere, causing them to be warmer, this flips in southern hemisphere

Land-water heating differences

Water: surface transparent, sunlight penetrates all the way through, greater evaporation, takes more energy to warm up

Land: surface opaque, lower specific heat, less evaporation. Places further from water will have larger temperature range

Specific heat

amount of energy it takes to change an object 1 degree celsius

Maritime effect

The oceans moderate the temperature

Continental effect

refers to areas less affected by the sea and therefore having a greater range between max and min temps

Clouds and radiation

Clouds reflect solar radiation back to space, keep energy from entering or block energy from leaving

Global annual temperature ranges

Places furthest away from oceans have the greatest temp range

Wind chill temperature

wind increases the sensible heat away from the body, makes it seem colder

Heat index

If there is more humidity (water in the air) it is harder for sweat to evaporate and we are hotter

How much of earth is water?

71% of earth is water, and 96.5% of water is in the oceans

Amount of water vapor

the highest near equator and surface (similar pattern to temp in troposphere)

humidity

the amount of water vapor in the air

specific humidity

measures the amount of water vapor in the air at a given location, local parcel of air. mass of water vapor relative to mass of all gases

saturation specific humidity

the maximum amount of water vapor the air can hold

saturation

when the amount of water vapor in an air parcel is equal to the maximum amount possible

Clausius-Clapeyron relation

The saturation values depend only on temperature

Relative humidity

measures how close an air parcel is to saturation

Cause saturation: addition

when saturation is achieved by addition of water vapor it is accomplished through local evaporation (maybe advection)

Mixing

Cold air with warm air: two unsaturated air parcels mix and form saturated

Cooling

air temperature is cooled to its dew point

Dewpoint

The temperature to which the air must be cooled for saturation to occur

The higher the specific humidity

the higher the dewpoint temperature

after dewpoint/frostpoint

This excess water vapor must be shed through condensation

the hotter the air is

the more water vapor it can hold

Latent heat

energy is required (consumed) by water for evaporation

the sling psychrometer

how humidity is measured; dry bulb gives air temp, wet bulb gives humidity

Diabatic processes

Involved in the addition or removal of energy

Adiabatic

Process in which temperature changes but no heat is added or removed from a surface, important for cloud formation

Ideal gas law

pressure = temperature x gas constant x density

Direct relationship between

density and pressure, temperature and pressure

Inverse relationship between

density and temperature

How clouds form

An air parcel rises when its density is less than of the surrounding air. warm air is bouyant and rises, cool air sinks

• parcel rises and expands and cools, does work on atmosphere, cools down

• as it moves down, work happens on parcel to compress, and it heats

Dry adiabatic lapse rate (DAR)

10 degrees celsius per kilometer. warming and cooling due to changing pressure of unsaturated parcel

Moist adiabatic lapse rate (MAR)

varies with temp and moisture, but 6 degrees celsius/km on average

Environmental lapse rate

lapse rate of surrounding air, observed temperature distribution, varies over time and space

Unstable air

Continues to rise until reaching an altitude where the surrounding air has a density and temp similar to its own

Stable air

resists movement upward, returns to where it came from

Conditionally unstable

stability depends on whether air parcel is saturated or not

absolutely unstable

the DAR and MAR both cool slower than the surrounding atmosphere

absolutely stable

the DAR and MAR both cool faster than the surrounding atmosphere, will always be colder and sink down

Conditionally stable

The DAR cools faster but MAR cools slower than atmosphere (how atmosphere is most of the time). moves up using its own power

perturbation

initial push air parcel

Factors that influence the ELR

• advection of cold and warm air at different levels

• advection of an air mass with a different environmental lapse rate

Inversion layers

warmer and less dense, so they have more stable air, which stops a parcel from rising more

Fog

a cloud with its base at or near the earth’s surface, often diabatic processes (heat is exchanged between air parcel and environment)

High altitude clouds

primarily adiabatic processes (expansional cooling, no heat exchanged with environment)

Evaporation fog

cold air over warm water, evaporation water quickly condenses

Precipitation fog

precipitation evaporates as it falls to surface, increasing SH and decreasing SSH through evaporative cooling

Advection fog

warm moist air is advected over a cold surface, air is cooled to dewpoint temperature

Radiation fog

Occurs on clear nights when longwave radiation can escape freely through atmosphere, causing temperatures to cool to dewpoint

Upslope fog: rocky mountains, CO

warm moist air near the surface ascend slope, cooling adiabatically to dewpoint

Localized convection

Occurs when differential heating at the surface causes air to life (ex. pavement) the air expands and cools as it lifts, causing cloud development

Convergence (lifting)

Occurs when there is a horizontial movement of air into a region, have nowhere to go but up

Orographic uplift

When a mass of air is deflected up one side of a hill or mountain (causes rain shadow on the other side)

Frontal lifting

Occurs when two air masses converge at the front. Warmer, less dense air forced over cooler, denser air along a boundary called a front

High clouds

Bases above 6000 m

Cirrus

(high) composed of ice crystals (little water vapor high up in the atmosphere) wispy appearance due to low water content and cold temperatures

Cirrostratus

(high) occurs when cirrus stretches across the sky, flat clouds (may form halo around sun when light is refracted)

cirrocumulus

(high) resembles fish scales, bunch of cotton balls

Middle clouds

bases between 2000 and 6000m, can be close to height where 0 degrees celsius occurs (half above half below)

Altostratus

(middle) typically thick enough to almost fully obscure the sun or moon and blanket the entire sky, dark gray mid level clouds

Altocumulus

Typified by a banded and billowy (heaps) middle level clouds

Low clouds

bases below 2000 m

Stratus

Clouds are layered and uniform, can blanket larger areas, flat

Stratocumulus

low, layered clouds with puffy “heaps” and some vertical development

Nimbostratus

low clouds produce light rain, dark, thick, and cover whole sky

Fair weather cumulus

clouds form when rising air parcels have areas of weak downdrafts between them, can see shapes (not unstable enough to cause storm)

Cumulus congestus (low to middle)

cumulus clouds grow larger when atmosphere is unstable, each cloud tower replaced by next, higher into atmosphere (see on airplane)