Place these notes into your Meteorology Notebook Chapter 19 Review Place these notes into your Meteorology Notebook

Because water vapor molecules are lighter than nitrogen or oxygen molecules humid air is lighter than an equal volume of dry air at the same temperature. Forces inside your body push outward, balancing the weight of the air column that stretches from your head to the top of the atmosphere. Air exerts pressure in all directions. A barograph records and measures air pressure on a chart.

Jet Stream

Jet Stream

Jet Stream

For every 5 km increase in elevation above sea level, a barometer reading will drop by about 50%. Wind direction can be affected by a pressure gradient, the Coriolis effect, and friction in the atmosphere. In the Southern Hemisphere, the Coriolis effect causes an object moving freely across Earth’s surface to turn to the object’s left. The Coriolis effect is greatest near the poles.

Air above the poles is cold and sinking. The Coriolis effect affects how strong winds are the least. Altitude, roughness of the Earth’s surface, and pressure gradients cause more changes in the wind. Wind speed is measured by an anemometer Winds between the doldrums and horse latitudes that are warm and relatively steady in direction and speed are known as trade winds.

The following are weaknesses in the three-celled model of Earth’s wind patterns. The circulation at mid-latitudes has been simplified. Continents and seasons are not taken into account. Upper-level winds have been simplified.

During the Northern Hemisphere summer, the intertropical convergence zone can occur as far north as 30º N. When the coastal land is warmer than the nearby water, a sea breeze forms. In the doldrums, where surface winds from two hemispheres meet, there is hot, humid air with little or no wind. Lines on a map that joins points having the same sea-level air pressure at a given time are called isobars.

If Earth did not rotate and there were no Coriolis effect, surface wind direction would primarily be from the poles to the equator. Sea breezes, land breezes, and mountain breezes are examples of local winds.

Be able to label the high and low pressure regions, and indicate the direction of flow on each circulation cell of the three celled-circulation model. High Low High Low High Low High

Essay #1 During the nineteenth century, many New Hampshire farmers found that crops grew better and that temperatures were milder on mountainsides than in valleys. Explain why. Mountain and valley breezes help to regulate the temperature on a mountain. At night, the cool mountain air sinks and flows into the valley. During the day, hot mountain air rises and a breeze flows up from the valley.

Essay #2 Why can an umbrella salesperson in India take long vacations during the winter? How might air pressure during the winter affect umbrella sales? During the winter in India, cold sinking air over the continent flows toward low pressure over the sea, producing cold, dry winds. The lack of moisture makes for a dry season, which could affect umbrella sales.