Properties of Heat and Light
Insulation = material having a high resistance to the flow of electric current, to prevent leakage of current from a conductor.
= Any material that offers resistance to heat transmission. When insulation is placed in walls, ceilings or floors it reduces the loss or gain of heat from outside sources.
Conduction = The transfer of heat energy through a substance or from one substance to another by direct contact of atoms or molecules.
= Heat transfer through a solid material by contact of one molecule to the next. Heat flows from a higher-temperature area to a lower-temperature one.
Convection = the transfer of energy by the flow of a liquid or a gas
= A method of transferring heat energy by the movement of the heated substance itself.
= Currents created by heating air, which then rises and pulls cooler air behind it
Radiation = energy that is radiated or transmitted in the form of rays or waves or particles
= the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay
Transmission = the act of sending a message; causing a message to be transmitted
= communication by means of transmitted signals
Reflection = the phenomenon of a propagating wave (light or sound) being thrown back from a surface
Refraction = The process by which the direction of a ray of light changes as it passes obliquely from one medium to another.
= The tendency of a wave to bend as it passes from one transparent medium to another.
All About Clouds
Stratus Clouds
The word stratus comes from the Latin word that means "to spread out." Stratus clouds are horizontal, layered clouds that stretch out across the sky like a blanket. Sometimes a layer of warm, moist air passes over a layer of cool air. Stratus clouds often form at the boundary where these layers meet. Where two such layers of air meet, the warm air is cooled. If the warm air is cooled below its dew point, the excess water vapor condenses to form a blanket - like layer of stratus clouds. If the layers of air are very large, the stratus clouds may extend for many kilometers across the sky.
Cumulus Clouds
The word cumulus comes from the Latin word for a heap or a pile. Cumulus clouds are puffy in appearance. They look like large cotton balls. Cumulus clouds usually form when warm, moist air is forced upward. As this air rises, it is cooled. If it is cooled below its dew - point temperature, condensation will occur. The size of a cumulus cloud depends on the force of the upward movement of air and the amount of moisture in the air. The largest cumulus clouds are caused by very strong upward movements of warm, moist air. The clouds that produce heavy thunderstorms in summer are a form of cumulus clouds called cumulonimbus. Cumulonimbus clouds may extend upward for hundreds of meters.
Cirrus Clouds
Cirrus clouds are a third general type of cloud. The word cirrus comes from the Latin word for a tuft or curl of hair. Cirrus clouds are very wispy and feathery looking. They form only at high altitudes, about 7 km above the earth's surface. Cirrus clouds are composed of ice crystals and are so thin that sunlight can pass right through them.
High clouds (Family A)
* Cirrocumulus
* Cirrus cloud
* Cirrostratus
Middle clouds (Family B)
* Altostratus
* Altocumulus
Low clouds (Family C)
These are found up to 2,000 m (6,500 feet) and include the stratus (dense and grey). When stratus clouds contact the ground, they are called fog.
Clouds in Family C include:
* Cumulus
* Stratocumulus
* Nimbostratus
* Stratus
Vertical clouds (Family D)
These clouds can have strong up-currents, rise far above their bases and form at many heights.
Clouds in Family D include:
* Cumulonimbus (associated with heavy precipitation and thunderstorms)
* Cumulus
* Pyrocumulus
Storms and Hurricanes
Cyclone = a rotating mass of air with minimum pressure in its center. It is n area of low atmospheric pressure characterized by rotating and converging winds and ascending air
A storm is any disturbed state of an astronomical body's atmosphere, especially affecting its surface, and strongly implying severe weather. It may be marked by strong wind, thunder and lightning (a thunderstorm), heavy precipitation, such as ice (ice storm), or wind transporting some substance through the atmosphere (as in a dust storm, snowstorm, hailstorm, etc).
Once upon a time, hurricanes seemed to come from nowhere. Now, weather satellites track them to their sources. Atlantic hurricanes, for example, originate off the coast of West Africa, where "tropical disturbances" form in low-pressure zones.
A disturbance may intensify into a "tropical depression," surrounded by a high-pressure zone that helps contain the storm, which is centered on a column of rising air. Winds are moderate: 21 to 35 miles per hour.
Once the winds exceed 35 miles per hour, the system, now called a "tropical storm," gets an alphabetical name. The storm now has the circular structure of a hurricane, although it may not become one.
Powered by solar heat that was stored in the ocean and then transferred into the warm, moist air, the tropical storm becomes a hurricane once winds exceed 74 miles per hour.
You might expect a rotating storm to whirl itself apart, but hurricanes feed on themselves to gain strength. In their energy flow, hurricanes resemble large thunderstorms. But while thunderstorms can start over land or water, hurricanes only start over water. Hurricanes also last much longer, carry far greater energy, and cause much greater destruction.
Stages of Development
from disturbance to hurricane
Hurricanes evolve through a life cycle of stages from birth to death. A disturbance graduates to a more intense stage of development by attaining a specified sustained wind speed.
Tropical Disturbance:
The birth of a hurricane, having only a slight circulation with no closed isobars around an area of low pressure. Tropical disturbances commonly exist in the tropical trade winds at any one time and are often accompanied by clouds and precipitation.
Tropical Depression:
If sustained winds increase to at least 20 knots, a disturbance is upgraded to a tropical depression. Surface wind speeds vary between 20 and 34 knots and a tropical depression has at least one closed isobar that accompanies a drop in pressure in the center of the storm.
Tropical Storm:
If sustained wind speeds increase to at least 35 knots, a tropical depression is upgraded to a tropical storm. Surface wind speeds vary between 35 and 64 knots and the storm becomes more organized. Tropical storms resemble the appearance of hurricanes due to the intensified circulation.
Hurricane:
As surface pressures continue to drop, a tropical storm becomes a hurricane when sustained wind speeds exceed 64 knots. A pronounced rotation develops around the central core as spiral rain bands rotate around the eye of the storm. The heaviest precipitation and strongest winds are associated with the eye wall.
SIGNAL NO. WIND SPEED (kph) TIME OF OCCURRENCE
1 = 30 - 60 at least 36 hours
2 = 60 - 100 at least 24 hours
3 = 100 - 185 at least 18 hours
4 = >185 at least 12 hours
World Climates
Three major climate groups show the dominance of special combinations of air-mass source regions.
Group I
Low-latitude Climates: These climates are controlled by equatorial a tropical air masses.
• Tropical Moist Climates (Af) rainforest
Rainfall is heavy in all months. The total annual rainfall is often more than 250 cm. (100 in.). There are seasonal differences in monthly rainfall but temperatures of 27°C (80°F) mostly stay the same. Humidity is between 77 and 88%.
High surface heat and humidity cause cumulus clouds to form early in the afternoons almost every day.
The climate on eastern sides of continents are influenced by maritime tropical air masses. These air masses flow out from the moist western sides of oceanic high-pressure cells, and bring lots of summer rainfall. The summers are warm and very humid. It also rains a lot in the winter
o Average temperature: 18 °C (°F)
o Annual Precipitation: 262 cm. (103 in.)
o Latitude Range: 10° S to 25 ° N
o Global Position: Amazon Basin; Congo Basin of equatorial Africa; East Indies, from Sumatra to New Guinea.
• Wet-Dry Tropical Climates (Aw) savanna
A seasonal change occurs between wet tropical air masses and dry tropical air masses. As a result, there is a very wet season and a very dry season. Trade winds dominate during the dry season. It gets a little cooler during this dry season but will become very hot just before the wet season.
o Temperature Range: 16 °C
o Annual Precipitation: 0.25 cm. (0.1 in.). All months less than 0.25 cm. (0.1 in.)
o Latitude Range: 15 ° to 25 ° N and S
o Global Range: India, Indochina, West Africa, southern Africa, South America and the north coast of Australia
• Dry Tropical Climate (BW) desert biome
These desert climates are found in low-latitude deserts approximately between 18° to 28° in both hemispheres. these latitude belts are centered on the tropics of Cancer and Capricorn, which lie just north and south of the equator. They coincide with the edge of the equatorial subtropical high pressure belt and trade winds. Winds are light, which allows for the evaporation of moisture in the intense heat. They generally flow downward so the area is seldom penetrated by air masses that produce rain. This makes for a very dry heat. The dry arid desert is a true desert climate, and covers 12 % of the Earth's land surface.
o Temperature Range: 16° C
o Annual Precipitation: 0.25 cm (0.1 in). All months less than 0.25 cm (0.1 in).
o Latitude Range: 15° - 25° N and S.
o Global Range: southwestern United States and northern Mexico; Argentina; north Africa; south Africa; central part of Australia.
Group II
• Mid-latitude Climates: Climates in this zone are affected by two different air-masses. The tropical air-masses are moving towards the poles and the polar air-masses are moving towards the equator. These two air masses are in constant conflict. Either air mass may dominate the area, but neither has exclusive control.
• Dry Midlatitude Climates (BS) steppe
Characterized by grasslands, this is a semiarid climate. It can be found between the desert climate (BW) and more humid climates of the A, C, and D groups. If it received less rain, the steppe would be classified as an arid desert. With more rain, it would be classified as a tallgrass prairie.
This dry climate exists in the interior regions of the North American and Eurasian continents. Moist ocean air masses are blocked by mountain ranges to the west and south. These mountain ranges also trap polar air in winter, making winters very cold. Summers are warm to hot.
o Temperature Range: 24° C (43° F).
o Annual Precipitation: less than 10 cm (4 in) in the driest regions to 50 cm (20 in) in the moister steppes.
o Latitude Range: 35° - 55° N.
o Global Range: Western North America (Great Basin, Columbia Plateau, Great Plains); Eurasian interior, from steppes of eastern Europe to the Gobi Desert and North China.
• Mediterranean Climate (Cs) chaparral biome
This is a wet-winter, dry-summer climate. Extremely dry summers are caused by the sinking air of the subtropical highs and may last for up to five months.
Plants have adapted to the extreme difference in rainfall and temperature between winter and summer seasons. Sclerophyll plants range in formations from forests, to woodland, and scrub. Eucalyptus forests cover most of the chaparral biome in Australia.
Fires occur frequently in Mediterranean climate zones.
o Temperature Range: 7 °C (12 °F)
o Annual Precipitation: 42 cm (17 in).
o Latitude Range: 30° - 50° N and S
o Global Position: central and southern California; coastal zones bordering the Mediterranean Sea; coastal Western Australia and South Australia; Chilean coast; Cape Town region of South Africa.
• Dry Midlatitude Climates (Bs) grasslands biome
These dry climates are limited to the interiors of North America and Eurasia.
Ocean air masses are blocked by mountain ranges to the west and south. This allows polar air masses to dominate in winter months. In the summer, a local continental air mass is dominant. A small amount of rain falls during this season.
Annual temperatures range widely. Summers are warm to hot, but winters are cold.
o Temperature Range: 31 °C (56°F).
o Annual Precipitation: 81 cm. (32 in.).
o Latitude Range: 30° - 55° N and S
o Global Position: western North America (Great Basin, Columbia Plateau, Great Plains); Eurasian interior.
• Moist Continental Climate (Cf) Deciduous Forest biome
This climate is in the polar front zone - the battleground of polar and tropical air masses. Seasonal changes between summer and winter are very large. Daily temperatures also change often. Abundant precipitation falls throughout the year. It is increased in the summer season by invading tropical air masses. Cold winters are caused by polar and arctic masses moving south.
o Temperature Range: 31 °C (56 ° F)
o Average Annual Precipitation: 81 cm (32 in).
o Latitude Range: 30° - 55° N and S (Europe: 45° - 60° N).
o Global Position: eastern parts of the United States and southern Canada; northern China; Korea; Japan; central and eastern Europe.
Group III
• High-latitude climates: Polar and arctic air masses dominate these regions. Canada and Siberia are two air-mass sources which fall into this group. A southern hemisphere counterpart to these continental centers does not exist. Air masses of arctic origin meet polar continental air masses along the 60th and 70th parallels.
• Boreal forest Climate ( Dfc) taiga biome
This is a continental climate with long, very cold winters, and short, cool summers. This climate is found in the polar air mass region. Very cold air masses from the arctic often move in. The temperature range is larger than any other climate. Precipitation increases during summer months, although annual precipitation is still small.
Much of the boreal forest climate is considered humid. However, large areas in western Canada and Siberia receive very little precipitation and fall into the subhumid or semiarid climate type.
o Temperature Range: 41 °C (74 °F), lows; -25 °C (-14 °F), highs; 16 °C (60 °F).
o Average Annual Precipitation: 31 cm (12 in).
o Latitude Range: 50° - 70° N and S.
o Global Position: central and western Alaska; Canada, from the Yukon Territory to Labrador; Eurasia, from northern Europe across all of Siberia to the Pacific Ocean.
• Tundra Climate (E) tundra biome
The tundra climate is found along arctic coastal areas. Polar and arctic air masses dominate the tundra climate. The winter season is long and severe. A short, mild season exists, but not a true summer season. Moderating ocean winds keep the temperatures from being as severe as interior regions.
o Temperature Range: -22 °C to 6 °C (-10 °F to 41 °F).
o Average Annual Precipitation: 20 cm (8 in).
o Latitude Range: 60° - 75° N.
o Global Position: arctic zone of North America; Hudson Bay region; Greenland coast; northern Siberia bordering the Arctic Ocean.
• Highland Climate (H) Alpine Biome
Highland climates are cool to cold, found in mountains and high plateaus. Climates change rapidly on mountains, becoming colder the higher the altitude gets. The climate of a highland area is closely related to the climate of the surrounding biome. The highlands have the same seasons and wet and dry periods as the biome they are in.
Mountain climates are very important to midlatitude biomes. They work as water storage areas. Snow is kept back until spring and summer when it is released slowly as water through melting.
o Temperature Range: -18 °C to 10 °C (-2 °F to 50°F)
o Average Annual Precipitation: 23 cm (9 in.)
o Latitude Range: found all over the world
o Global Position: Rocky Mountain Range in North America, the Andean mountain range in South America, the Alps in Europe, Mt. Kilimanjaro in Africa, the Himalayans in Tibet, Mt. Fuji in Japan.
