Focus on Aviation: Lightning and Aircraft

Understanding Weather and Climate (7th Edition) (MasteringMeteorology Series) by Edward Aguado, James E. Burt

Evaporation and Condensation

Figure 5–2b shows what happens when we remove the covering on the liquid water surface. Without the covering, some of the molecules at the surface can escape into the overlying volume as water vapor. The process whereby molecules break free of the liquid volume is known as evaporation. The opposite process is condensation, wherein water vapor molecules randomly collide with the water surface and bond with adjacent molecules. At the beginning of our hypothetical experiment, no condensation could occur because no water vapor was present. As evaporation begins, however, water vapor starts to accumulate above the surface of the liquid.

At the early stages of evaporation, the low water vapor content prevents much condensation from occurring, and the rate of evaporation exceeds that of condensation. This leads to an increase in the amount of water vapor present. With increasing water vapor content, however, the condensation rate likewise increases. Eventually, the amount of water vapor above the surface is enough for the rates of condensation and evaporation to become equal, as shown in Figure 5–2c. A constant amount of water vapor now exists in the volume above the water surface due to offsetting gains and losses by evaporation and condensation. The resulting equilibrium state is called saturation. When this equilibrium exists in the atmosphere, the air is said to be saturated.

The state of saturation described here can occur whether or not air (or other gases, for that matter) exists in the container. In other words, the water vapor is not “held” by the air (although this erroneous statement is frequently made). Water vapor is a gas, just like the other components of the air. Thus, it does not need to be “held” by air any more than the oxygen, nitrogen, argon, and other gases of the atmosphere need to be held by water vapor! When the air is saturated, there is simple an equilibrium between evaporation and condensation; the dry air plays no role in achieving this state. It is also important to realize that the exchange of water vapor and liquid described here applies as well to the change of phase between water vapor and ice. The change of phase directly from ice to water vapor, without passing into the liquid phase, is called sublimation. The reverse process (from water vapor to ice) is called deposition (Figure 5–3).

Understanding Weather and Climate (7th Edition) (MasteringMeteorology Series) 7th Edition by Edward Aguado (Author), James E. Burt (Author)

Cream of Pork Chops Recipe

Prep Time: 15mins
Total Time: 1 hr+
Servings: 2 servings


Ingredients:

• 6 mini pork chops (0.38lbs) OR 2 regular sized pork chops
• 1 can of cream of chicken / cream of chicken with herbs soup
• Instant white rice

Preparation:

• Brown pork chops in a pan

• Once browned, add the can of cream of chicken soup + the 1 can of water
• Simmer 30-60mins (the longer you simmer the more tender the pork chops will be) (feel free to add extra water to keep the "gravy"/soup from burning/evaporating too much)

• When ready to eat, make instant rice and serve under the pork chops with the "gravy"/soup

ENJOY!

Composition & Structure of the Atmosphere

Introduction

·       Meteorology = the study of the atmosphere and the processes (such as cloud formation, lightning and wind movement) that cause what we refer to as the “weather”

·       Weather is distinct from climate in that the former deals with the short-term phenomena and the latter with the characteristic long-term patterns.

The Atmosphere, Weather and Climate

·       Atmosphere = a mixture of gas molecules, small suspended particles of solid liquids, and falling precipitation. 

·       Climatology

o   Relies on averages taken over a number of years in order to gauge typical atmospheric conditions for locations across Earth’s surface.

o   Also want to know about variability of the weather elements.

o   Frequencies of occurrences of weather events (such as extreme heat, hail or lightning) are also aspects of climates.

o   Concerned with changes in Earth’s climate and the factors responsible for those changes.

Thickness of the Atmosphere

·       ­How high is the sky?

o   There is no definitive answer. However, because Earth’s atmosphere becomes thinner at higher altitudes, even at heights of several hundred kilometers above sea level, there is some air and, hence, an atmosphere. But we have no way to establish its upper boundary because there is no universally accepted definition of how much air in a given volume constitutes the presence of an atmosphere.

Horizontal Winds	Vertical Winds
-       Primary motion over large areas -       Are typically hundreds to thousands of times greater than vertical wind speeds	-       Hardest to detect and forecast -       Determine much of the atmospheric behavior

Composition of the Atmosphere

·       The atmosphere is composed of a mixture of invisible gases and a large number of suspended microscopic solid particles and water droplets.

·       Molecules

o   Molecules of gases can be exchanged between the atmosphere and the Earth’s surface by physical processes (i.e. volcanic eruptions) or by biological processes (i.e. plant and animal respiration).

o   Can be produced and destroyed by purely internal processes (i.e. chemical reactions between gases)

o   Steady State / Equilibrium Condition = input rate is equal to the output rate

o   Dynamic Equilibrium = molecules cycling in and out of the atmosphere

o   Residence Time = average length of time that individual molecules of a given substance remain in the atmosphere

·       Homosphere

o   The lowest 80 km (50 mi) of the atmosphere

o   Vertical motions are more important than gravitational settling thus processes (other than settling) under gravity must explain any variations present.

o   Reflects the homogenizing role of wind and other motions

o   Gases are often categorized as being permeant or variable, depending on whether or not their concentration is uniform.

§  Permanent Gases = found everywhere in nearly the same proportion.

§  Variable Gases = distribution is uneven in both time and space.

·       Heterosphere = layer of the atmosphere (above the homosphere) where gases segregate according to molecular weight

·       Permanent Gases

o   Make up more than 99% of the atmosphere

o   Nitrogen (most abundant gas)

§  78% of all permanent gasses volume or 75.5% of their mass

§  Largely unreactive

§  Occurs primarily as paired nitrogen atoms bonded together to form single molecules denoted N₂

§  Isotopes = variants of an element with different neutron counts

o   Oxygen (second most abundant gas)

§  21% of the volume of the atmosphere and 23% of its mass

§  Crucial to the existence of virtually all forms of life

§  Dynamic Oxygen = paired oxygen atoms

o   Nitrogen + Oxygen = 99% of all permanent gases

·       Variable Gases

o   Water vapor (most abundant) is 1% of the total volume

§  Condenses to a liquid at relatively low levels in the homosphere

§  Not uniformly distributed with altitude—at higher altitudes, water vapor is even more rare

§  Hydrologic Cycle (water cycle)

§  Source of moisture to form clouds

§  Very effective absorber of energy emitted by the Earth’s surface (radiant energy) thus making it one of the “greenhouse gases”

Adiabatic Lapse Rates

What do you know about the Wet Adiabatic Lapse rate?

-       Less than dry adiabatic lapse rate

The more it slants = greater lapse rate 

Lapse rate = Rate of cooling

What’s the difference between the Dry and Wet Adiabatic Lapse Rate?

-   Unsaturated à reaches LCL à Saturated

-   Latent “Hidden” heat - The heat either released or absorbed as a result of a change of state.

-   When a cloud forms….

o   The water vapor reaches the LCL à Temperature decreases à It’s doing work à slows the rate of cooling

-   Water vapor condenses à latent heat is released

Mixing ratio (w) - A measurement of the amount of water vapor in the air of a given sized quantity of dry air. Grams of vapor per kilogram of dry air.

W = Water vapor in the box

-   Dewpoint Lapse Rate = As it goes up it decreases = 2 deg C / km

-   Dew point (Td) - The temperature to which air must cool at constant pressure in order for air to reach saturation (commonly dew to form); indicates moisture content.

Adiabats & Potential Temperature

Dry Adiabat = 333

·         Potential Temperature – A measure of heat. It is the temperature air would be if brought dry adiabatically to 1000 mb.

·         How much warmer will the potential temperature increase?

o   Has hidden heat, Lift up, pressure decreases, starts expanding, starts making hidden heat into real heat, which is determined by how much latent heat is left in the parcel

o   Wet adiabatic line will be parallel to the dry adiabatic line

§  Vapor starts condensing which makes latent heat turn into real heat

·         Latent heat becoming real is what is increasing the potential temperature -  delta = measure of real heat