Lessons 26 · 1 lessons · P. Gulyamov, R. Qurbonniyozov, M. Avezov, N. Saidova. Geography (Introductory Course of Physical Geography), Grade 5. Revised and expanded 5th edition. “Mitti yulduz”, Tashkent, 2020
26
Practical work: wind and humidity
Textbook: §26, pp. 88–90
GoalPractise drawing a wind rose and calculating relative humidity and the moistening degree.
New words
wind rose · shamollar guliwind direction · shamol yo‘nalishirelative humidity · nisbiy namlikmoistening degree · namlanish darajasi
Explanation
A wind rose is a diagram showing the directions from which winds blew at a place during a certain period. To draw it, lines are drawn from a point along the 8 directions of the horizon, a scale is chosen (for example 1 cm = 2 days) and the number of days the wind blew from each direction is marked on that scale; the line ends are then joined. The longest line shows the most frequent wind direction. Relative humidity = absolute humidity : maximum capacity × 100 %. Moistening degree = yearly precipitation : yearly evaporation; the most favourable value for plants is between 0.9 and 1.1. During the work record the data in a table, do each calculation step by step in the notebook and check the answer.
Worked examples
30-day data (a teaching example): N 3, NE 2, E 4, SE 3, S 5, SW 4, W 6, NW 3 days. The total is 30; the most frequent is the westerly (6 days); with 1 cm = 2 days the west line is 3 cm.
In one place yearly precipitation is 500 mm and evaporation 1000 mm: the moistening degree is 500 : 1000 = 0.5 – moisture is lacking. In another place 900 : 900 = 1 – favourable for plants.
Class activity
“Wind rose”: from five days of class observations record the wind directions and draw a common wind rose on the board; find the most frequent direction.
Practice
1
From the example data, on how many days in total did the wind blow from the west and south-west?
10
2
With 1 cm = 2 days, how many cm long is the west line if the wind blew from the west for 6 days?
3
3
At +30 °C the air has 24 g of vapour (maximum 30 g). What is the relative humidity in %?
80
4
What are the plant-growing conditions where yearly precipitation is 150 mm and evaporation is 2000 mm, and why?
Unfavourable: the moistening degree is very low (≈ 0.08) and moisture is lacking.