Temperature, Buoyancy, and Vertical Motion Temperature, Pressure, and Density Buoyancy and Static Stability Temperature “Lapse Rates” Rising & Falling.

Slides:



Advertisements
Similar presentations
Cloud Development and Precipitation
Advertisements

Cloud Development and Forms
Ch 5 – Vertical Motion & Stability
Atmospheric Stability
Ch Atmosphere Atmosphere – 99% Nitrogen and Oxygen
Atmospheric Moisture and Stability
Atmospheric Stability Hot air and buoyancy. Outline  Pressure in fluids –Pascal’s principle  Buoyancy –Archimedes’ principle –Density and Temperature.
Stability & Movement Figure 7.1 A rock, like a parcel of air, that is in stable equilibrium will return to its original position when pushed. If the rock.
Atmospheric Stability
Atmospheric Stability and Cloud Formation. RECAP Mechanical equilibrium: stable, unstable, neutral. Adiabatic expansion/compression: no heat exchange.
Tephigrams ENVI1400 : Lecture 8.
Stability & Skew-T Diagrams
Textbook chapter 2, p chapter 3, p chapter 4, p Stability and Cloud Development.
Lecture 5.2: Stability Are you stable or unstable? Does it depend on the situation?
Outline Further Reading: Chapter 06 of the text book - stability and vertical motions - five examples - orographic precipitation Natural Environments:
NATS 101 Lecture 12 Vertical Stability
Temperature, Pressure, Density and Vertical Motion Adapted from Scott Denning’s presentation for CSU CMMAP course Summer 2007 By Jim Barnaby Summer 2008.
MET 61 1 MET 61 Introduction to Meteorology MET 61 Introduction to Meteorology - Lecture 6 Stability Dr. Eugene Cordero San Jose State University W&H:
Moisture and Atmospheric Stability
Atmospheric Moisture and Stability
METEO 003 LAB 6 Due Friday Oct. 17 th. Chapter 8 Question 1 a,b,c Radiosonde: instrument carried by a weather balloon to measure atmospheric variables.
Water in the Atmosphere Water vapor in the air Saturation and nucleation of droplets Moist Adiabatic Lapse Rate Conditional Instability Cloud formation.
CHAPTER 4 MOISTURE AND ATMOSPHERIC STABILITY. “Too Much, Too Little, Too Bad” All life on Earth is directly tied to acquiring water in forms of sufficient.
Lapse Rates and Stability of the Atmosphere
Thermodynamics, Buoyancy, and Vertical Motion
The Atmosphere Basic Structure.
Chapter 6 – Cloud Development and Forms. Cloud Formation Condensation (i.e. clouds,fog) results from:
Atmospheric Stability
Thermodynamics, Buoyancy, and Vertical Motion Temperature, Pressure, and Density Buoyancy and Static Stability Adiabatic “Lapse Rates” Convective Motions.
 Important gases in atmosphere as they relate to atmospheric pressure  State Change of water  Humidity and dew points affecting weather  Explain motion.
Chapter 4 Moisture and Atmospheric Stability. Steam Fog over a Lake.
The Atmosphere: An Introduction to Meteorology, 12th
Atmospheric Stability & Instability
MET 102 Pacific Climates and Cultures Lecture 5: Water and Rising Air.
CHAPTER 5 CLOUDS AND STABILITY CHAPTER 5 CLOUDS AND STABILITY.
Moisture and Atmospheric Stability … and Instability How does is relate to cloud development and precipitation?
Atmosphere Chapter 11.2 & 11.3.
Lab 6: Saturation & Atmospheric Stability
Moisture in the Atmosphere
Equation of State (a.k.a. the “Ideal Gas Law”) Direct relationship between density and pressure Inverse relationship between density and temperature Direct.
Weather State Objectives 4.c, 4.e, 4.h..
Key Terms and Concepts ELR--Environmental Lapse Rate 5°C-6.5°C/1000 m – temperature of the STILL air as you ascend through the troposphere. ALR--Adiabatic.
Weather & Climate LECTURE 2 Moisture in the Atmosphere Evaporation and Condensation: accompanied by absorption/liberation of heat evaporation: energy.
Weather
THE SUN’S ENERGY. Climatic interactions exist among Earth, ocean and weather systems. The Sun provides the energy that drives convection within the atmosphere.
5.01 Heating and Cooling of the Atmosphere
Water in the Atmosphere Lab 5 October 5, Water Is Important!!!
11.2- State of the Atmosphere Moisture in the Atmosphere
Chapter 6. Importance of Clouds  Release heat to atmosphere  Help regulate energy balance  Indicate physical processes.
Chapter 38 Weather.
Atmospheric Stability Terminology I Hydrostatic Equilibrium –Balance, in the vertical, between PGF and gravity –The general state of the atmosphere –Net.
Weather and Climate Unit Investigative Science. * Meteorologists describe properties of the atmosphere using the following descriptors: * Temperature.
Atmospheric Stability The resistance of the atmosphere to vertical motion. Stable air resists vertical motion Unstable air encourages vertical motion.
Vertical Motion and Temperature Rising air expands, using energy to push outward against its environment, adiabatically cooling the air A parcel of air.
Meteo 3: Chapter 8 Stability and Cloud Types Read Chapter 8.
Chapter 6 Stability and Cloud Development. Stability & Cloud Development This chapter discusses: 1.Definitions and causes of stable and unstable atmospheric.
Chapter 18 Evaporation, Condensation, and Precipitation.
Chapter 4 Moisture and Atmospheric Stability
5.01 Heating and Cooling of the Atmosphere
Stability and Cloud Development
5.01 Heating and Cooling of the Atmosphere
Atmospheric Stability
Thermodynamics, Buoyancy, and Vertical Motion
Atmospheric Stability
Chapter 18.2 Cloud Formation.
Bellwork 4/10 Please, turn in your Sling Psychrometer Lab
Stability and Cloud Development
Atmospheric Stability & Instability
5.01 Heating and Cooling of the Atmosphere
Atmospheric Stability
Presentation transcript:

Temperature, Buoyancy, and Vertical Motion Temperature, Pressure, and Density Buoyancy and Static Stability Temperature “Lapse Rates” Rising & Falling Motions in the Air

What is Air Temperature? Temperature is a measure of the kinetic energy (speed) of air molecules as they bounce around High temperature air is made of fast molecules that deliver a lot of energy when they hit something Cold air is made of slower molecules that hit things less often and deliver a weaker wallop when they do The sensation of warmth is created by air molecules striking and bouncing off your skin surface

Temperature Scales In the US, we use Fahrenheit most often Celsius (centigrade) is a scale based on freezing/boiling of water Kelvin is the “absolute” temperature scale

How Atmospehric Temperature is Measured Helium-filled weather balloons are released from over 1000 locations around the world every 12 hours (some places more often) These document temperature, pressure, humidity, and winds aloft

Pressure Pressure is defined as a force applied per unit area The weight of air is a force, equal to the mass m times the acceleration due to gravity g Air pressure results from the weight of the entire overlying column of air!

Density (mass/volume) Same number of molecules and mass Sample 1 takes up more space Sample 2 takes up less space Sample 2 is more dense than sample 1 Sample 1 Sample 2

Pressure and Density Gravity holds most of the air close to the ground The weight of the overlying air is the pressure at any point

Changes in density drive vertical motion in the atmosphere and ocean. Less dense air rises when it is surrounded by denser air. -Think of a hollow plastic ball submerged under water. What happens when you release it? The ball is less dense than the water around it … Density is the Key to Buoyancy!

Buoyancy and Temperature Hot air has fast-moving molecules that spread out and occupy more space (volume) … so it is less dense! Cold air has slow-moving molecules that pack more closely together and take up less space … so it is more dense An air parcel rises in the atmosphere when its density is less than its surroundings So air that is warmer than its surroundings rises, and air that is colder than its surroundings sinks

Trading Height for Heat We can think of two kinds of energy in the air: potential energy (due to its height) internal energy (due to the motions of the molecules that make it up) Air can trade one kind of energy for the other, but conserves the overall total When air rises, it gains height but loses heat (cools) … when it sinks it loses height but gains heat (warms)

Hot Air Ballooning Contain some air in the balloon envelope Add some serious heat energy! Air expands and rises (some gets out the bottom) Balloon accelerates upward

Temperature, Density, and Convection Heating of the Earth’s surface during daytime causes the air to vertically mix

“Lapse Rate” The lapse rate is the change of temperature with height in the atmosphere Environmental Lapse Rate –The actual vertical profile of temperature (as measured on a tower or airplane or balloon) Dry Lapse Rate –The change of temperature that an air parcel would experience if it were displaced vertically with no condensation or heat exchange

Dry Lapse Rate Warming and Cooling due to changing pressure 10 degrees C per kilometer

Hiking Long’s Peak Fort Collins is 5000 feet above sea level Longs Peak is feet above sea level Climbing 9255 feet is almost 3000 m Dry lapse rate 10 °C / km, so should be 30 °C colder (=54 F) Suppose it’s 95 °F in FC today, 95 – 54 = 41 °F on Long’s!

Stability & Instability A rock, like a parcel of air, that is in stable equilibrium will return to its original position when pushed. A rock or parcel of air in unstable equilibrium will rush away from its initial position when pushed a little

Stability in the atmosphere Stable Unstable Neutral If an air parcel is displaced from its original height it can: Return to its original height - Stable Accelerate upward because it is buoyant - Unstable Stay at the place to which it was displaced - Neutral An Initial Perturbation

Why is stability important? Vertical motions in the atmosphere are a critical part of energy transport and strongly influence the hydrologic cycle Without vertical motion, there would be no precipitation, no mixing of pollutants away from ground level - weather would be totally boring! There are two types of vertical motion: –forced motion such as forcing air up over a hill, over colder air, or from horizontal convergence –buoyant motion in which the air rises because it is less dense than its surroundings

Vertical Motion and Temperature Rising air expands, using energy to push outward against its environment, cooling the air Air may be forced to rise or sink, and change its temperature relative to the air around it

Stability and the Dry Lapse Rate A rising air parcel cools according to the dry lapse rate (10 C per km) If rising, cooling air is: –warmer than surrounding air it is less dense and buoyancy accelerates the parcel upward … UNSTABLE! –colder than surrounding air it is more dense and buoyancy opposes (slows) the rising motion … STABLE!

Unstable Atmosphere The atmosphere is unstable if the actual lapse rate exceeds the dry lapse rate (air cools more than 10 C/km) This situation is rare in nature (not long-lived) –Usually results from surface heating and is confined to a shallow layer near the surface –Vertical mixing eliminates it Mixing results in a dry lapse rate in the mixed layer, unless condensation (cloud formation) occurs

What conditions make the air unstable? Warming of surface air –Solar heating of ground –Warm “advection” near surface –Air moving over a warm surface (e.g., a warm body of water) Cooling of air aloft –Cold “advection” aloft (thunder-snow!) –Radiative cooling of air/clouds aloft

Stable Atmosphere The atmosphere is stable if the actual lapse rate is less than the dry lapse rate (air cools less than 10 C/km) This situation is common in nature (happens most calm nights, esp in winter) –Usually results from surface cooling and is confined to a shallow layer near the surface –Vertical mixing or surface heating eliminates it

What conditions make the air stable? Radiative cooling of surface at night Advection of cold air near the surface Air moving over a cold surface (e.g., snowy ground, cold water, ice,) Warming of the air due to compression from subsidence (sinking)

Air Stability and Pollution When air is stable (cold near ground), pollution pools like water (cough cough) Unstable air (warm near surface) mixes pollution up up and away

Stability and Clouds Stable air (cold surface, warm aloft) resists vertical motion Unstable air (warm surface, cold aloft) amplifies vertical motion Flat (stratus) clouds Puffy (cumulus) clouds

Stability and Turbulence Daytime heating of the ground by the sun produces instability Strong vertical motion near ground is turbulent

Vertical Motion and Weather Sinking motion warms and dries the air, produces sunny weather Rising motion cools the air, condenses water, produces clouds & rain