Exam 1 - Weather and climate

Laws of radiation

Stefan-Boltzmann law, Wien's displacement law

What is saturation vapor pressure depends on?

Temperature of the air (warmer = hold more water vapor)

equilibrium radiative temperature

incoming solar radiation absorbed by the earth and its atmosphere would be equal to outgoing longwave radiation from the earth and its atmosphere

Global distribution of lapse rates

lower at the poles, higher at the equator

Which greenhouse gas is most prevalent+potent

Water vapor (abundant and potent)

What is dry adiabatic lapse rate

10 degrees Celsius per 1 km

Which gases contribute the most to GH effect?

Water vapor (most abundant)

Environmental Lapse rate

5 degrees Celsius per 1 km

What is the relation between water vapor pressure and water vapor content?

Actual vapor pressure is a measurement of the amount of water vapor in a volume of air and increases as the amount of water vapor increases. Air that attains its saturation vapor pressure has established an equilibrium with a flat surface of water. That means, an equal number of water molecules are evaporating from the surface of the water into the air as are condensing from the air back into the water.

Supergeostrophic/subgeostrophic flow

Air moves faster than geostrophic flow around high pressure (supergeostrophic); along a ridge Air moves slower than geostrophic flow around low pressure (subgeostrophic); along a trough

Air Movement

Air moves in westerly direction (deflects right in northern) (deflects left in southern)

Geostrophic Wind

Air under the influence of both the pressure gradient force and Coriolis force tends to move parallel to isobars in conditions where friction is low (1000 meters above the surface of the Earth) and isobars are straight. winds come about because pressure gradient force and Coriolis force come into balance after the air begins to move. This deflection continues until the pressure gradient force and Coriolis force are opposite and in balance with each other.

What are the effects of Albedo (high/low lats, ocean/land, snow seasons)

Albedo is not important at high latitudes in winter: there is hardly any incoming sunlight to worry about. It becomes important in spring and summer when the radiation entering through leads can greatly increase the melt rate of the sea ice. Ice, especially with snow on top of it, has a high albedo: most sunlight hitting the surface bounces back towards space. Water is much more absorbent and less reflective. So, if there is a lot of water, more solar radiation is absorbed by the ocean than when ice dominates.

albedo

Albedo is the fraction of solar energy (shortwave radiation) reflected from the Earth back into space. It is a measure of the reflectivity of the earth's surface

Arctic

Arctic warms faster b/c convection at poles increases when it heats, which makes moisture in air increase Snow, ice, water vapor feedback makes arctic warm more, and in turn, holds more moisture Since water vapor is potent GHG, it can hold heat better, feedback is reinforcing

Dry Adiabatic

As long a rising or sinking parcel remains unsaturated, the rate of adiabatic cooling or warming remains constant 10°C/1000m.

Based on the "leaky" one layer model, how can we change the climate (which forcings)?

As you can see from the difference in the above diagrams the only change is an increase in energy radiated back out into space. The one layer model assumes 100% GHG absorption, which is not the case. So by changing the amount of GHG in the atmosphere we can change the amount of heat radiated back into space and in conjunction the amount of heat trapped in our atmosphere Albedo, earth to sun ratio, solar irradiance

Radiative equilibrium

Assumes incoming radiative energy from the sun is equal to outgoing energy emitted by the planet -18degC = Radiative Equilibrium

Why absorption of solar radiation is not equally distributed throughout the year.

Because of the tilt of the Earth's axis, incoming solar radiation is not evenly distributed on the Earth's surface and seasonal changes occur

Effects of methane

Change in methane emissions brings very large relative change in atmospheric greenhouse

Which processes other than radiation contribute to lapse rate?

Convection, adiabatic processes

Wien's Law with cooler objects

Cooler objects emit most of their radiation at longer wavelengths; hence they will appear to be redder.

Adiabatic cooling

Cooling w/o any addition or extraction of energy, but due to pressure changes in x'atmosphere with changes in altitude Expands when floats up Contracts when descending due to atmospheric pressure Cooling associated w/ contraction and expansion of unsaturated air parcel = dry adiabatic cooling -10oC per vertical km

How can the absorbed solar energy be 239 W/m2 when the radiation from the surface is 390 W/m2? Where is the energy coming from?

Coz its absorbed by atmosphere

Environmental

Decrease in temperature usually occurs with increasing height through the troposphere About 6.5oC / km which means the atmosphere is conditionally unstable DALR > ELR > WALR Dalr = 10 deg C/km Elr = 6.5 deg C/km Walr = less than 6 deg C/km

Lapse rates (dry adiabatic, wet (moist) adiabatic, radiative, environmental)

Dry - 10℃/km Wet (air is unstable will cool slower than dry, and will be warmer) Radiative Environmental - Can change

Why it the emission curve not smooth?

Due to the portions of the electromagnetic spectrum (including visible light) that is trapped by free atoms or molecules in the path of the radiation, thus reducing their transmission. In the climate context, this is important for the greenhouse effect since water vapor, carbon dioxide and methane absorb certain wavelengths of infrared radiation.

Stefan Boltzmann Law

E=σT4 σ is the stefan-boltzmann constant σ=5.6704 × 10^−8 W/(m^2)(K^4)

Why is absorption of solar radiation not equally distributed over the Earth surface?

Earth is a sphere and aside from the part closest to the sun, where the rays of sunlight are perpendicular to the ground, its surface tilts with respect to the incoming rays of energy with the regions furthest away aligned in parallel to the radiation and thus receiving no energy at all

Why do we have seasons?

Earth is tilted and rotates around the sun, varying the level of solar radiation that Earth receives, thus causing seasons and seasonal changes. (Solstice and Equinox)

Why doesn't all of the energy leaving the sun reaches the Earth

Earth's Energy balance, describes how the incoming energy from the sun is used and returned to space. If incoming and outgoing energy are in balance, the earth's temperature remains constant.

radiation

Emission of energy from an object in the form of electromagnetic waves and photons. Solar radiation- originates from the sun, most of sun's radiation emitted at wavelengths between 1.0 and .1 microns (um)

How does Environmental lapse rate change over space/time?

Environmental lapse rate

What is saturation vapor pressure?

Evaporation rate is equal to condensation rate. The amount of pressure in the air parcel that can be attributed to the vapor Out of the total amount of air pressure, how much can be attributed to water vapor in the air parcel unique function of temperature, dew point temperature, because as the ground cools, dew will begin to form

If we increase CO2, what will change?

Global temperatures will rise as CO2 absorbs heat and is able to hold it for a long period of time (high heat coefficient). It will intensify the greenhouse gas effect

properties of pressure systems

HIGH pressure: subsidence / downward (vertical) and divergence / spreading out (horizontal) LOW pressure: ascent / upward (vertical) and convergence / contracting (horizontal)

Wien's Law with hotter objects

Hotter objects emit most of their radiation at shorter wavelengths; hence they will appear to be bluer. at any wavelength, a hotter object radiates more (is more luminous) than a cooler one

Troposphere vs surface heating and relation to lapse rates

If the lapse rate become le Nothing can go higher than the tropopause and stratosphere

Dalton's law of partial pressures

In a mixture of gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture.

latent heat

Latent heat is the energy absorbed by or released from a substance during a phase change from a gas to a liquid or a solid or vice versa

Which Greenhouse gas provide most ghg effect?

Methane

What is conduction

Molecules collide, and higher energy molecules excite lower energy molecules, and transfer kinetic energy

P=pRT

Pressure = density x R x temperature Where R is a constant

Geostrophic balance

Pressure gradient force and coriolis

What does equilibrium radiative temperature of the Earth depend on?

Radiative Equilibrium Temp = -18deg C

Vorticity = tendency of atmosphere to rotate

Relative- due to the rotation of the system with respect to the Earth. Spin occurs because object itself turns Planetary - the latitudinal value of the Coriolis force, spin of object requires rotation of earth Absolute - sum of relative and planetary

Sensible heat

Sensible heat is the energy required to change the temperature of a substance with no phase change. The temperature change can come from the absorption of sunlight by the soil or the air itself.

evaporation when temperature is negative?

Sublimination

What happens when we exceed saturation vapor pressure?

Supersaturation, temporary state, water vapor condenses until state of supersaturation is relieved

Inverse Square Law

The energy twice as far from the source is spread over four times the area, hence 1/4 the intensity.

first law of thermodynamics

The law of conservation of energy states that the total energy of an isolated system is constant; energy can be transformed from one form to another, but cannot be created or destroyed. The first law is often formulated by stating that the change in the internal energy of a closed system is equal to the amount of heat supplied to the system, minus the amount of work done by the system on its surroundings.

Pressure gradient force

The pressure gradient results in a net force that is directed from high to low pressure

Wet Adiabatic

The rate at which a saturated air parcel will cool or warm is called the wet (moist) adiabatic lapse rate (WALR)

Coriolis in northern vs. southern hemispheres.

Trade winds- south winds go southeast and northern winds go northwest

Atmospheric stability and vertical motion

Unstable - parcel is lighter and rises - T Parcel > T Air Stable - parcel is heavier and descends - T Parcel < T Air Neutral - parcel maintains

Stability of lapse rate

Values less than 5.5-6.0 degrees C/km ("moist" adiabatic) represent "stable" conditions, while values near 9.5 degrees C/km ("dry" adiabatic) are considered "absolutely unstable." In between these two values, lapse rates are considered "conditionally unstable." Conditional instability means that if enough moisture is present, lifted air parcels could have a negative LI (lifted index) or positive CAPE.

Why is moist (wet) adiabatic lapse rate smaller than dry Adiabatic lapse rate?

Water cools/heats slower than dry air

Hydrostatic equilibrium

When pressure gradient force = gravity This means no movement

temperature

a measure of the average kinetic energy of atoms and molecules for the given substance

density

a physical property of matter represented by ratio of mass to volume; units kgm-3

Temperature inversions

a thin layer of the atmosphere where the normal decrease in temperature with height switches to the temperature increasing with height. An inversion acts like a lid, keeping normal convective overturning of the atmosphere from penetrating through the inversion.

Coriolis force

an effect whereby a mass moving in a rotating system experiences a force (the Coriolis force ) acting perpendicular to the direction of motion and to the axis of rotation. On the earth, the effect tends to deflect moving objects to the right in the northern hemisphere and to the left in the southern and is important in the formation of cyclonic weather systems

horizontal pressure gradient

an expression for the magnitude of the force causing the molecules of air to move horizontally from the region of high pressure toward the region of lower pressure

What happens when you add latent heat, warming

condensation

How can we achieve saturation

decreasing the temperature (to dew point), or mix cool air into warm air, or add water content to the air.

ideal gas law (Pressure, density, temperature)

defined as one in which all collisions between atoms or molecules are perfectly eleastic and in which there are no intermolecular attractive forces. One can visualize it as a collection of perfectly hard spheres which collide but which otherwise do not interact with each other. In such a gas, all the internal energy is in the form of kinetic energy and any change in internal energy is accompanied by a change in temperature. An ideal gas can be characterized by three state variables: absolute pressure (P), volume (V), and absolute temperature (T).

Subsidence inversion

develops when a widespread layer of air descends. The layer is compressed and heated by the resulting increase in atmospheric pressure, and as a result the lapse rate of temperature is reduced.

What happens when you remove latent heat, Cooling

evaporation

Sublimination

evaporation when temperature is negative

How will the "leaky" model change if the albedo changes?

every arrow/aspect of the leaky model will change

Air movement in the upper troposphere

experiences changing temps, lapse rates change from negative to positive, inversion

heat

form of energy created by the combined internal motion of atoms in a substance. Heat energy depends on the speed of the particles, the number of particles (the size or mass), and the type of particles in an object.

Why does pressure reduce with altitude?

gravity. Pressure and altitude are inversely related. The gravitational attraction between the earth and air molecules is greater for those molecules nearer to earth than those further away - they have more weight - dragging them closer together and increasing the pressure (force per unit area) between them. Molecules further away from the earth have less weight (because gravitational attraction is less) but they are also 'standing' on the molecules below them, causing compression. Those lower down have to support more molecules above them and are further compressed (pressurised) in the process.

Pressure

high pressure anticyclone" and "low pressure cyclone" are tautological. Air in a low pressure system spirals in towards the centre at the surface where it rises and then spirals out high in the troposphere. Air in a low pressure system spirals inwards high in the troposphere, descends and spirals out at the surface. The direction of the spirals is opposite in the northern and southern hemispheres due to Coriolis. In the southern hemisphere, air at the surface spirals clockwise into a low and anticlockwise out of a high.

Why Southern hemisphere is warmer than the northern

land:water ratio Southern hemisphere has more water than land, so during the summers, the water heats up and since water is slow to heat, slow to cool, during the winters, the water keeps the land somewhat warmer. Northern hemisphere has hotter summers though because it has more land than water, so land absorbs heat faster, but also releases heat faster Ratios: North land:water = 40:60 South land:water = 20:80

equinoxes

night and day of approximately equal length all over the earth and occurring about March 21 (vernal equinox or spring equinox) and September 22 (autumnal equinox) astronomical event in which the plane of Earth's equator passes through the center of the Sun, which occurs twice each year, around 20 March and 23 September.

Atmospheric composition

nitrogen (78%), oxygen (21%), argon (1%), and then trace amounts of carbon dioxide, neon, helium, methane, krypton, hydrogen, nitrous oxide, xenon, ozone, iodine, carbon monoxide, and ammonia. Lower altitudes also have quantities of water vapor.

Adiabatic heating

occurs in the Earth's atmosphere when an air mass descends, for example, in a katabatic wind, Foehn wind, or chinook wind flowing downhill over a mountain range. When a parcel of air descends, the pressure on the parcel increases. Due to this increase in pressure, the parcel's volume decreases and its temperature increases as work is done on the parcel of air, thus increasing its internal energy, which manifests itself by a rise in the temperature of that mass of air. The parcel of air can only slowly dissipate the energy by conduction or radiation (heat), and to a first approximation it can be considered adiabatically isolated and the process an adiabatic process.

adiabatic cooling

occurs when the pressure on an adiabatically isolated system is decreased, allowing it to expand, thus causing it to do work on its surroundings. When the pressure applied on a parcel of air is reduced, the air in the parcel is allowed to expand; as the volume increases, the temperature falls as its internal energy decreases. Adiabatic cooling occurs in the Earth's atmosphere with orographic lifting and lee waves, and this can form pileus or lenticular clouds.

How will the "leaky" model change if the gas concentration changes?

only arrows with greenhouse gases will change

Arctic (Polar) amplification

phenomenon that any change in the net radiation balance (for example greenhouse intensification) tends to produce a larger change in temperature near the poles than the planetary average

How when where Negative vs Positive Lapse rate

positive when the temperature decreases with elevation, zero when the temperature is constant with elevation, and negative when the temperature increases with elevation (temperature inversion)

What is environmental lapse rate

rate at which the air temperature surrounding us (or the air parcels) would be changed if we were to climb upward into the atmosphere. Dry adiabatic lapse rate = 10°C/1km Moist lapse rate = 6.5 degrees C per 1 km

Coriolis effect amount of deflection and latitudes

slowly blowing winds will be deflected only a small amount, while stronger winds will be deflected more. Likewise, winds blowing closer to the poles will be deflected more than winds at the same speed closer to the equator. The Coriolis force is zero right at the equator

Explain the emission curve for the Earth

spectrum of frequencies of electromagnetic radiation emitted due to an atom or molecule making a transition from a high energy state to a lower energy state.

Boiling occurs when ...

the PRESSURE of the evaporating gas EQUALS THE PRESSURE OF THE SURROUNDING GAS.

pressure

the amount of force over a given area; units m-1kgs-2 Pa (Pascal); 1mb=100Pa

solstices

the astronomical event that occurs twice each year (in June and December) as the Sun reaches its highest or lowest excursion relative to the celestial equator on the celestial sphere. Longest and shortest days, with reference to sunlight.

Wien's displacement law

the black body radiation curve for different temperatures peaks at a wavelength inversely proportional to the temperature.

convection

the circular motion that happens when warmer air or liquid — which has faster moving molecules, making it less dense — rises, while the cooler air or liquid drops down. major factor in weather. The sun heats the earth's surface, then, when cooler air comes into contact with it, the air warms and rises, creating an upward current in the atmosphere. That current can result in wind, clouds, or other weather. Convection currents within the earth move layers of magma, and convection in the ocean creates currents. Convection ovens use fans to circulate heat so that whatever you're cooking cooks faster and more evenly.

Stefan-Boltzmann law

the total radiant heat energy emitted from a surface is proportional to the fourth power of its absolute temperature. The law applies only to blackbodies, theoretical surfaces that absorb all incident heat radiation

greenhouse effect

the trapping of the sun's warmth in the planet's lower atmosphere due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet's surface.

blackbodies

theoretical surfaces that absorb all incident heat radiation

Vertical motion-related pressure changes create?s

thermally driven circulation land/sea breezes

Explain vertical temperature profile of the atmosphere

troposphere is hotter near the Earth's surface because heat from the Earth warms this air. Stratosphere has layer of ozone, which absorbs ultraviolet radiation from sunlight which results in warming. Mesosphere, decrease in temperature with altitude because of the decreases in the density. Thermosphere warmed by absorption of solar X-rays by the nitrogen and oxygen molecules, temperature increases with altitude

Greenhouse Gas atmospheric composition

water vapor (60%), carbon dioxide (CO2) (26%), methane (CH4) & nitrous oxide (N2O) (6%), tropospheric ozone (O3) (8%) and chlorofluorocarbons (CFCs)

What is "atmospheric window"

wavelengths of the electromagnetic spectrum that can be transmitted through the earth's atmosphere. Atmospheric windows occur in the visible, infrared, and radio regions of the spectrum

Where is the atmosphere the thickest, thinnest

where its warmer, wetter, more dense Where its colder, drier, less dense