Geology

Week 4 Deserts Lab Report

15.4     Contrasting climate in Fig. 15.5 are due to the prevailing winds emanating from the oceans heavily laden by the moisture from the sea. The land heats faster than the seawater and therefore during the day when the sun is above the land the warm air carrying moisture rises while the cold air descends down onto the sea. As moisture-laden air- mass rise on the mountainous region, the moisture condenses causing rain on the side facing the sea. As a result, the opposite side called the rain shadow experiences dry weather. Consequently, the leeward side becomes dry as opposed to the windward side. The vegetation cover shows the difference in climate as shown in Fig. 15.5.

15.6     A hawk or an eagle heads for a spot beneath a cumulus cloud to rise after getting tired because during the formation of the cumulus cloud, the relative humidity gets over 100% causing water vapor to condense. As the vapor condenses, it produces latent heat, which warms the air causing further convection. The rising warm air beneath the cloud produces a lift to the bird hence it gains in altitude without expending much energy.

15.7     Bernoulli principle applies to fluid flow through a pipe. The dirt mounted at the entrance and exits of the prairie dog village assists in ventilating the village. As wind blows across the village, the small heap causes air to enter into the village and as the wind blows past the high heap, it deflects upwards causing low pressure. Hence forming the exit of the air

15.8     Nights in arid areas are very cold because the dry air contains no or little vapor hence the temperature varies rapidly: the air stores little heat, and when the sun sets (no heat source) it become cold.

15.14   Prevailing wind direction indicated by barchans dunes in Figure 15.14 is South- East

15.16   Dune A is asymmetrical with the circular southern part having more sand and a sharp northern part. The vegetation on the northern side causes the deposition of less sand as compared to the southern part of the dune.

15.18   The steeper side of the dune is southeast side

15.19   The kind of dune traversed with topographic profile is Barchan

15.20   The wind direction of the Lakeside region blow from NW

Lab Summary

Atmospheric circulation controls the location of deserts around the world. The agent of circulation is the wind, which moves moisture from the oceans onto land. The following are the principles by which air obtains moisture and deposit it on land.

1. Sea water evaporates into the air (humidifying the air)
2. Land heats faster than seawater hence warms air over it more than the seawater
3. The less dense warm air rises while the cold dense air sinks
4. Warm air with great moisture content cools and loses its moisture as rain or snow

The descending cold air promotes dryness while rising warm air promotes precipitation. Subtropical deserts arise because of the dryness at latitudes between 20o and 30o north and south. The sun heats the equatorial regions more than Polar Regions because solar heat per unit area is great at low latitudes and less reflection into space.

Rain shadows also cause deserts. In this case, the circulation of the atmosphere drives the prevailing winds across mountains. Dry conditions occur at the leeward side. Cold-water coasts experience dry desert conditions due to cold, dry air breeze from the sea onto warm land. The cold dry air carries little moisture.( Monroe, Reed & Richard, 2006, p. 556)_

Animals know about air. For instance, the hawk and the eagle fly close to the cumulus clouds to gain height with little effort. The prairie dogs village architecture. The main aim of the architecture is to have good air circulation.

The worst part of the lab assignment is on Figure 15.14. The sand dunes are not so clear and the distinction in parts of the sand dune is invisible. For better understanding of the section, clear topographic maps are inevitable.

Work cited

Morris, John D. The Geology Book. Green Forest, AR: Master Books, 2006.

Monroe, James S, Reed Wicander, and Richard Hazlett. Physical Geology: Exploring the Earth; [the Wrath of Hurricane Katrina ; Could You Survive a Tsunami?; Catastrophic Earthquakes; Global Warming]. Belmont [u.a.: Thomson, 2006.

The Geology Lab manual