Class Notes

Chap.(24-25)

On a clear, calm night, when the temperature of the air at the surface drops to the same value as the dew point temperature one might expect dew not snow. Weather ahead of a warm front is generally rainy and foggy. The ozone layer protects us from ultraviolet radiation. Chlorofluorocarbons in the stratosphere are a problem because they destroy ozone which protects us from harmful radiation. The earth's present atmosphere is mostly nitrogen, with a fair amount of oxygen.

Above the earth's atmosphere there exist regions of high-energy, charged particles called the Van Allen belts. Closely spaced isobars on a map indicate strong pressure gradient. In the northern hemisphere the wind circulation in a low is clockwise, spiraling inward and outward. The amount of water vapor in the air at any one time and place is called humidity. The amount of water vapor in the air compared with the greatest amount that could be present at a given temperature is relative humidity. "Tornado Alley" seems to be centered on Kansas and Oklahoma.

The gas removed from the atmosphere in the process of photosynthesis is carbon dioxide. The process that effectively regulates Earth's average temperature is the greenhouse effect. When the relative humidity is 100%, the air temperature is equal to the dew-point temperature. Mostly the Water vapor of the atmosphere varies with temperature. The atmospheric conditions of the lower troposphere is reffered to as weather. The percentage of insolation reaching Earth's surface is approximately 50%.

The principal gases responsible for the greenhouse effect are carbon dioxide and water vapor. The process by which plants convert carbon dioxide to oxygen is called photosynthesis. The most abundant gas in the atmosphere is nitrogen. It is known that the Ozone atmospheric gas absorbs ultraviolet radiation. The gas added to the atmosphere in the process of photosynthesis is oxygen. Photosynthesis involves the replenishing of oxygen depleted by animals. The blueness of the sky results from preferential scattering of light by gas molecules. Atmospheric pressure is measured by means of a barometer. The relative humidity is 100% when the actual moisture content is equal to the maximum moisture capacity.

Wind speed is measured by means of an anemometer. The horizontal movement of air is called wind. Early explorers from countries in southern Europe sailed to America with the aid of northeast tradewinds. A low-pressure belt exists in the equatorial region because of rising warm air; these latitudes are often referred to as the doldrums. The rate at which air temperature changes with altitude is called the lapse rate. The deflection produced by the Coriolis force is greatest toward the poles. A wind is named after the direction or region from which it comes. A wispy, fibrous form of cloud is the cirrus. Air circulation around a cyclone in the Northern Hemisphere as viewed from above is counterclockwise. A velocity-dependent force that acts on air motion is friction.

The northeast tradewinds lie in the latitude region of 0 to 30. The boundary of an advancing cold air mass over a warmer surface is cold front. When two advancing fronts meet, a typical result is a stationary front. High winds and low temperatures accompanying precipitation can give rise to a blizzard. Lightning damage chiefly comes from cloud-to-ground discharge. A tropical storm becomes a hurricane when its wind speed reaches 74 mi/h. When a body of air takes on physical characteristics that distinguish it from the surrounding air, it is referred to as an air mass. If a tornado is sighted in your neighborhood, you should seek shelter in your basement or in a stairwell. The midwest regions of the United States are most likely to develop tornadoes.

The boundary between two air masses is called a front. In general, radar is not capable of measuring or indicating temperature. Lines of constant pressure on a weather map are called isobars. On average, meteorologists are correct in their weather predictions about 80% of the time. Doppler radar is replacing conventional radar in weather forecasting because it can measure wind speeds. The infrared region of the electromagnetic spectrum, outside the visible, is useful for satellite-based meteorology.

About 78% of the air is composed of nitrogen We live in the troposphere part of the Earth's atmosphere. When an air sample is at its dew point, the air is completely saturated. The order of the regions of the atmosphere by increasing altitude is troposphere, stratosphere, mesosphere. Energy is trapped in the troposphere by a process known as the greenhouse effect. The actual amount of water vapor in a given sample of air as measured in gr/ft^3 is called absolute humidity. Localized heating gives rise to convection cycles. An anticyclone rotates clockwise in the Northern Hemisphere. The cloud root name cummulus refers to heap. The cumulonimbus cloud belongs to vertical development cloud family. In a temperature inversion, the temperature increases with altitude in the troposphere. A type of precipitation other than rain associated with thunderstorms is hail.

The two main distinguishing characteristics of an air mass are temperature and moisture content. The cold type of front has the greatest average speed.The boundary between any two air masses with different physicalcharacteristics is often referred to as a squall line. The sharpest change in weather conditions is usually associated with a cold front. Lightning that occurs below the horizon or behind clouds so that the clouds themselves appear to be illuminated with flickering flashes is called heat lightning. The most violent localized storm is the tornado. Regional precipitation and severe storms are commonly monitored by conventional and Doppler radar.